Hundreds of rebels from northern Syria managed to enter the besieged city of Qusair on Friday, activists said, to help opposition forces battling government troops backed by the Lebanese terrorist group Hezbollah.
The Syrian Observatory for Human Rights said hundreds of fighters from the Tawheed brigade, an Islamist group that is powerful in Aleppo in the north, had entered the town.
The brigade confirmed the report on its Facebook page.
The two-week battle for Qusair is aimed at securing supply routes near the Syrian-Lebanese frontier, which both sides accuse the other of using to bolster their forces inside Syria.
Syrian opposition captured a military airport in the city of Homs, Al Jazeera TV channel reported on Thursday.
According to the TV channel, after fighting between the Syrian army and the opposition military airport Daba is completely under the control of the opposition.
It is reported that at least 150 people were killed during the fighting.
Syrian troops backed by pro-government gunmen fought fierce battles with rebels on Saturday in a strategic area in Homs province near the Lebanese border, activists and state media in Damascus reported.
The latest fighting came as U.S. officials said the Obama administration was poised to send millions more in non-lethal military aid to rebels trying to oust President Bashar Assad.
The clashes around the contested town of Qusair, close to the Syria-Lebanon boundary, had intensified over the past two weeks amid a fresh offensive by the Syrian army and a pro-government militia known as Popular Committees, backed by the Lebanese militant Hezbollah group.