Egypt's military council is currently holding a crisis meeting which was joined by leading opposition figure Mohammed ElBaradei and religious leaders, military sources said on on Wednesday.
But the political wing of Egypt's ruling Muslim Brotherhood refused an invitation to meet the armed forces commander, military and party sources said.
"We do not go to invitations (meetings) with anyone. We have a president and that is it," said Waleed al-Haddad, a senior leader of the Freedom and Justice Party told Reuters.
The meeting was being held hours before the expiry of a deadline set by the army for rival politicians to find a solution to the country's political crisis. The source said the meeting was being attended by senior commanders of the armed forces.
The deadline is at 4:30 pm (1430 GMT) for the Islamist leader to "meet the demands of the people" -- who took to the streets in their millions on Sunday demanding he go -- or face army intervention.
The army is expected to issue a statement after the deadline expires, a source close to the military told AFP.
Armored vehicles have secured central Cairo studios of state television, security sources told Reuters. Staff not involved in working on live broadcasts had left the building, the sources added.
The powerful armed forces on Monday issued Mursi the 48-hour ultimatum -- which expires at 4:30 pm (1430 GMT) -- for the Islamist leader to "meet the demands of the people" following mass protests calling for his resignation.
In a statement that was headlined “The Final hours,” Egypt’s high command said on Wednesday that the army was ready to sacrifice blood to defend the Egyptian people against “terrorists or fools” as the death toll mounted in protester clashes.
The post on the official Facebook page of the Supreme Council of the Armed Forces (SCAF), headed by armed forces chief General Abdel Fattah al-Sisi, said: "We swear to God that we will sacrifice even our blood for Egypt and its people, to defend them against any terrorist, radical or fool."
The statement was issued three hours after Mursi gave a televised address to reject the ultimatum from Sisi.
A military source said the statement made clear that the armed forces would not abandon their demands, according to Reuters.
Mursi insisted on his ‘constitutional legitimacy” during the address and called on the army to withdraw its ultimatum to intervene if the political parties do not resolve differences.
The president also said he stood ready to “give my life” to defend constitutional legitimacy, echoing comments by a senior leader of the Muslim Brotherhood who urged supporters to be ready to sacrifice their lives to prevent a coup.
In the speech, which continued after more than 40 minutes, he admitted his first year in office had been difficult and he faced challenges from ‘corrupt remnants” of the old regime.
In a response to a military ultimatum to share power with his opponents, he said he had tried such dialogue before and had been unsuccessful. But he insisted he would continue fulfilling the duties to which he had been democratically elected.
‘The people chose me in free and fair elections,” Mursi said, adding that he would “continue to shoulder his responsibilities” as Egypt struggles with the legacy of decades of authoritarian rule.
The president said that respect for the constitutional order was the “only guarantee against further bloodshed,” in a veiled attack against an ultimatum issued by the army for him to strike a deal with his opponents or have one imposed.
Death toll in Cairo University clash rises
The spar between the presidency and the military came as the death toll in violence involving Islamist supporters of Mursi near Cairo University rose to 17.
State television quoted a Health Ministry spokesman saying that 200 people were wounded, while security sources said pro-Mursi demonstrators clashed with security forces.
Witnesses heard shotgun and rifle fire and teargas enveloped the area. Television pictures showed ambulances taking away casualties, small fires burning and hundreds of men, many with the beards typical of Mursi’s Islamist supporters, some of them weeping and others chanting slogans.
Meanwhile, Supporters and opponents of Mursi clashed on the streets of Alexandria on Tuesday (July 2) throwing rocks and glass at each other.
For the up-to-the-minute news on the Egyptian uprising, click here.
- Live from Egypt: latest developments
- Egypt’s sports minister quits after anti-Mursi protests
- Egypt boosts army presence on border with Gaza
- Brotherhood leader calls for 'martyrdom' to stop Egypt coup
- Egypt’s Pope hails protesters taking back ‘stolen revolution’
- Salafists in Egypt call for early elections to avoid ‘civil war’
- Egypt shares riskier after violence but foreigners may bargain-hunt