As many as 38 people have been shot dead by the Syrian security forces, Al Arabiya reported citing Syrian activists at the Local Coordination Committees.
The dead people were mostly in Hama, Daria, Mudamiya in Damascus, Deraa, Telkakh and Baalaba in Homs.
More than 100,000 protesters performed a sit-in in Douma as the Arab observers toured the city, Syrian activists said.
Huge protests were organized in most of the Syrian cities after the activists called for a “Friday of Marching to the Freedom Squares.”
Syrian forces were accused of firing nail bombs Friday to disperse protesters as tens of thousands of people flooded streets across the country to make their voices heard to Arab monitors, according to AFP.
Protesters called for the ouster and prosecution of President Bashar al-Assad, whose autocratic regime has been blamed for the deaths of more than 5,000 people since pro-reform protests erupted in March.
“This Friday is different from any other Friday. It is a transformative step. People are eager to reach the monitors and tell them about their suffering,” activist Abu Hisham in Hama told Reuters.
Activists urged monitors, who started this week a mission to implement an Arab League peace plan, to protect civilians from the regime’s wrath.
“We urge you to make a clear distinction between the assassin and the victim,” activists of the Syrian Revolution 2011 said in a statement posted on their Facebook page.
“Our revolution which was launched nine months ago is peaceful,” they said.
The United Nations said Friday it expects Syrian authorities to grant unfettered access and complete cooperation to Arab observers as bloodshed continues amid a crackdown on protesters.
“It is critical that the observer mission be given unhindered access and full cooperation by the government of Syria, and that its independence and impartiality be fully preserved,” U.N. spokesman Martin Nesirky said.
“We hope that the League of Arab States, under the able stewardship of its secretary-general and its membership, will take all steps possible to ensure that its observer mission will be able to fulfill its mandate in accordance with international human rights law standards.”
Heavy clashes, meanwhile, broke out between Syrian security forces and army defectors in the Damascus suburb of Douma on Friday, Syrian Observatory for Human Rights said.
Huge demonstrations rocked northwestern Idlib province and Douma, a Damascus suburb where protesters clashed with security forces who fired “nail bombs” to disperse them, said the Observatory.
At least 24 protesters were hurt when security forces fired “nail bombs to disperse tens of thousands of demonstrators in Douma,” the watchdog said, adding that the protesters “hurled stones” in retaliation.
“An activist in the city told the Observatory that he was hurt by shrapnel from those bombs,” the Britain-based group said in a statement received by AFP in Nicosia.
The reported use of nail bombs could not be independently verified.
In Douma, security forces also fired “stun grenades and tear gas” at protesters as 60,000-70,000 demonstrators headed to city hall, where Arab League observers visited the previous day.
It was the “biggest ever demonstration” in the restive suburb since March, it added.
Further north in Idlib province, which borders Turkey, more than 250,000 protesters took the streets in various locations, the Observatory reported.
Protests also took place in Homs, which activists have dubbed the “martyr” city as hundreds have died there in a government crackdown on dissent over the past few months.
In the Damascus neighborhood of al-Kadam, security forces fired live rounds of ammunition at worshippers who emerged from midday prayers apparently to prevent them from joining the protests, said the Observatory.
Protests in Aleppo, Syria’s second city in the north and economic hub, was “brutally” crushed by regime loyalists, it added.
The Observatory’s Rami Abdul Rahman told AFP activists are determined to make their voices heard to the monitors despite the bloody crackdown which activists say has killed more than 100 people since monitors arrived Monday.
“The Arab League’s initiative is the only ray of light that we now see,” said Abdel Rahman.
The mission has been tainted by some controversy, with some opposition members unhappy with the head of the observers General Mohammed Ahmed Mustafa al-Dabi -- a veteran Sudanese military intelligence officer.
Dabi this week ruffled feathers by saying Syrian authorities were so far cooperating with the mission and by describing his visit to Homs as “good.”
For some, Dabi is a controversial figure because he served under Sudan's President Omar al-Bashir who is wanted by the International Criminal Court for alleged war crimes committed in Darfur region.
“The observers must remain in the cities they visit to protect civilians,” said prominent human rights lawyer Haytham Maleh who is also a member of the main opposition Syrian National Council.
Speaking to Arab news channels, Maleh said the Arab League must increase the number of monitors to ensure they can verify Assad’s regime is implementing all the terms of the plan to end the violence.
Around 66 monitors are currently in Syria but there are plans to deploy between 150 and 200 observers.
“The presence of the observers in Homs broke the barrier of fear,” Abdul Rahman said in reference to some 70,000 demonstrators who flooded the streets of the central city Tuesday when the monitors kicked off their mission.
Western powers have urged Syrian to give them full access and Britain’s minister for the Middle East and North Africa Alistair Burt echoed those concern on Thursday.
Damascus must “meet fully its obligations to the Arab League,” including withdrawing security forces from cities, he said.
But Syria’s key ally Russia -- which has resisted Western efforts to push through the U.N. Security Council tough resolutions against Damascus -- said Friday it was happy with the mission so far.
“Judging by the public statements made by the chief of the mission (Sudanese general Mustafa) al-Dabi, who in the first of his visits went to the city of Homs ... the situation seems to be reassuring,” the Foreign Ministry said on its website.
Activist video from Homs over the months has depicted a trail of death and destruction sowed by the military, with hundreds of killings of civilians reported.
“Unfortunately, reports show that the violence has continued in Syria over the past few days,” Britain’s Minister for the Middle East and North Africa, Alistair Burt, said, according to Reuters.
“I urge the Syrian government to meet fully its obligations to the Arab League, including immediately ending the repression and withdrawing security forces from cities. The Syrian government must allow the Arab League mission independent and unrestricted access ...” Burt said.
In Brussels, a spokesperson for European Union foreign policy chief Catherine Ashton said the EU also “urges Syria to comply with the action plan of the Arab league in all its components” including “an immediate end of violence, the release of political prisoners, pulling the military out of cities.”
The mission has so far failed to end Syria’s nine-month orgy of violence in response to demands for Assad to step down, although it was never advertised as a peacekeeping operation.
An Arab League member from a Gulf State played down expectations for the mission.
Even if its report turns out to be negative it would not “act as a bridge to foreign intervention” but simply indicate that “the Syrian government has not implemented the Arab initiative,” the delegate told Reuters.
“The delegation is not meant to search or inspect anything other than this. It is not a fact-finding mission or an investigative committee ... The commission is meant to tell the League if Syria has committed to withdrawing its military from cities and to check if those who were detained during recent events have been released, and if Arab and international media are able to report on the situation freely or not.”
Syria says it is fighting Islamist militants steered from abroad who have killed more than 2,000 of its security forces personnel. Activist sources do not dispute that there has been a significant toll among the security forces.