Rami Abdul-Rahman of the Britain-based Syrian Observatory for Human Rights said local activists told him fighting was restricted to the area near the mosque, but that no fighters entered the site itself. The Observatory relies on reports from a network of activists in Syria.
Aleppo has been the scene of intense fighting, particularly since rebels launched a new offensive two weeks ago to try to dislodge regime troops. The fighting has devastated large areas of the city of 3 million, Syria's former business capital.
Earlier, Syrian activists also said the rebel units of the Free Syrian Army took control of Maaret al-Numan, a strategic city along the main highway in Idlib province that connects the central city of Homs with Aleppo to the north and the capital Damascus.
Abdul-Rahman said the rebels took control of the city late Tuesday. He said the rebels control the western entry into the city, while the military is massing troops along the eastern outskirts for a possible counter offensive.
Fadi Yassin, an activist in Maarat al-Numan, told The Associated Press on Skype that rebels were in control of the city, although fierce fighting continued around the military barracks on Wednesday, three days after the opposition launched a "liberation battle."
"The city has been liberated," Yassin said. "All liberation battles start with small cities and then move on to the major cities."
Holding onto Maaret al-Numan would be a significant achievement for the rebels, enabling them to cut the army's main supply route to Aleppo and Homs, both of which came under bombardment from the regime's helicopters and artillery on Wednesday, according to activists.
The Anadolu news agency reported fighting between Syrian rebels and forces loyal to Syrian President Bashar Assad's regime around the town of Azmarin, in Idlib province, across from the Turkish border. It said Syrians were fleeing homes in the Azmarin region, some crossing into Turkey by boat over the Orontes River, which runs along the border.
Footage from Anadolu showed women, children and elderly men being transported from Syria to Turkey on makeshift rafts and boats.
Private NTV television reported that explosions and automatic weapon fire could be heard in Turkey's Hatay province, coming from Azmarin. It said rebels were clashing with some 500 Syrian government soldiers, and that at least 100 rebels had been injured, some of whom had been brought to Turkey for treatment.
Some 99,000 Syrians, mostly women and children, have sought refuge in Turkey since the start of the conflict.
Also on Wednesday, state-run news agency SANA said Assad appointed Sattam Jadaan al-Dandah as Syria's new ambassador to Iraq. The report did not say when al-Dandah would travel to Baghdad. His predecessor, Nawaf Fares, defected in July, becoming the most senior diplomat to abandon Assad's regime during a bloody 18-month uprising that has morphed into a bloody civil war.
Meanwhile, the U.N. envoy on Syria, Lakhdar Brahimi, arrived in Jeddah, Saudi Arabia, on Wednesday on the first stop of his diplomatic tour of the Middle East. His spokesman Ahmad Fawzi said Brahimi would "hold wide-ranging talks on the prolonged crisis in Syria."
Barbara Surk and Zeina Karam in Beirut and Frank Jordans in Istanbul contributed to this report.
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