The United States said on Tuesday it was evaluating allegations of chemical weapons use in Syria after the Syrian government and the opposition accused each other of using such weapons near Aleppo.
Washington dismissed charges that the opposition had used chemical weapons in the two-year-old conflict.
“We are looking carefully at allegations of ... chemical weapons use, we are evaluating them,” White House spokesman Jay Carney told reporters.
“We have no evidence to substantiate the charge that the opposition has used chemical weapons,” he said.
“We are deeply skeptical of a regime that has lost all credibility and we would also warn the regime against making these kinds of charges as any kind of pretext or cover for its use of chemical weapons.”
President Bashar al-Assad’s government and rebel forces accused each other Tuesday of using chemical weapons for the first time.
“Terrorists fired rockets containing chemical materials on Khan al-Assal in Aleppo province,” the state news agency SANA and Syrian state television reported.
Syria's Information Minister Omran al-Zohbi called the attack a “dangerous escalation,” while state television said 25 people were killed and around 100 injured in the incident.
A spokesman for the Syrian rebels denied its fighters had used banned weapons, instead blaming Assad's regime for a deadly long-range missile attack that caused “breathing problems.”
Key Assad ally Moscow said it had “information” from Damascus that rebels had used chemical weapons, while Washington said there was “no evidence” the insurgents had staged their first chemical attack and warned it would be “totally unacceptable” for the regime to use such arms.
Britain, meanwhile, said it was looking into the reports and that if they were true, it would “revisit” its approach to the two-year conflict.
“We have seen those reports, they haven't yet been fully verified,” Britain's U.N. Ambassador Mark Lyall Grant told reporters on his way into a U.N. Security Council meeting on Afghanistan.
“But clearly if chemical weapons were used then that would be abhorrent and it would require a serious response from the international community,” he said.
Syria state television showed ambulances arriving at a hospital in Aleppo carrying the wounded, with medical officials and residents saying that the attack involved “toxic gas”.
“We have neither long-range missiles nor chemical weapons. And if we did, we wouldn't use them against a rebel target,” mainstream rebel Free Syrian Army spokesman Louay Muqdad told AFP.
“There are many casualties and many injured have breathing problems,” Muqdad said in Istanbul, where Syria's opposition has gathered to pick a rebel prime minister.
The Syrian Observatory for Human Rights, a Britain-based watchdog, confirmed that a ground-to-ground missile had been fired at an army position in Khan al-Assal, but there was no information on whether it contained chemical material.
It said the attack had killed 16 soldiers and 10 civilians.
The international community has expressed repeated concern over the possibility that Assad's regime would use its chemical weapons against the insurgents, and there are also fears the stocks could fall into the hands of militants if the regime loses control over them.
The Syrian conflict, now entering its third year, has killed some 70,000 people and forced millions to flee from their homes, according to the United Nations.
'No dialogue' with Assad
The United States on Tuesday welcomed the election of a long-time Texas resident as the Syrian rebel prime minister, voicing hopes he can foster “unity and cohesion among the opposition.”
US officials “know and respect” Ghassan Hitto from his work with the Syrian coalition on humanitarian efforts in Syria, State Department spokeswoman Victoria Nuland told reporters, although she refused to confirm he was an American citizen.
The rebels' new premier, Hitto, used his inaugural speech in Istanbul to reiterate there would be no dialogue with Assad's regime.
“We confirm to the great Syrian people that there will be no dialogue with the Assad regime,” said Hitto, who is now tasked with setting up an interim government to administer rebel-held areas in the strife-torn country.
Hitto was chosen early Tuesday by a majority of the main opposition National Coalition members, after hours of consultations.
But the vote was not without controversy, as several coalition members accused the powerful Muslim Brotherhood of backing his candidacy.
The election came some two months after coalition chief Ahmad Moaz al-Khatib proposed talks with regime officials with conditions, including that some “160,000 detainees” be released.
“The regime ended that proposal (for talks), not the opposition,” coalition chief Khatib told AFP.
In a speech laying out the new government's priorities, Hitto called the regime “a gang” that “destroyed the country”.
“The main priority we have before us is to make use of all tools at our disposal to bring down the Assad regime,” the 50-year-old said, while pledging to offer “all possible assistance” to residents living in areas free from army control.
The opposition intends to help administer daily life in large swathes of rebel territory mired in poverty and insecurity.