State news reported that 15 people were killed after a car bomb exploded in a government-held district in Homs on Sunday. Syria's state run SANA news agency described the bomb blast as a "terrorist attack."

For the past six months, the Syrian army has kept the mainly Sunni Arab rebel-held districts around the center of Homs under suffocating siege.

Meanwhile, heavy rocket attacks have killed at least 10 in Deir al-Asafir, 12 kilometers east of Damascus, according to activists.

Security contacts told the Reuters news agency that President Bashar Assad's forces launched an offensive in a move to seal central Damascus off from the suburbs. So far, the army's assault appears to have staved off a rebel advance into central Damascus.

Limited airport activity resumes

In a sign that the government had regained some control, EgyptAir said it was resuming flights to Damascus and Aleppo on Monday after a three-day halt in which Damascus airport was effectively closed due to unrest. The airline's head said conditions were stable.

No comment was immediately available from Emirates Airline, which also suspended its flights indefinitely.

Rebels claim the army has used the Damascus International Airport to bring in weapons. Intelligence reported earlier this year that Iran, Assad's main backer, had been using civilian aircraft to fly military equipment and personnel through Iraqi airspace into Syria.

Syria's uprising has grown increasingly bloody in recent months, and activists say that more than 40,000 have been killed. Assaults saw 200 die Saturday alone, according to the opposition-linked Syrian Observatory for Human Rights.

News from Syria is difficult to independently verify as authorities have barred most foreign media from the country since a pro-democracy uprising started in March last year.

mkg/hc (AFP, Reuters, AP, dpa)