BEIRUT: Syrian rebels and troops fought fierce battles over a keenly contested neighbourhood of Homs on Tuesday, as fresh clashes broke out on the road linking Damascus to its international airport, activists said.

The fighting in Homs was focused on the Khaldiyeh district and comes one week into a massive army and pro-regime militia assault to reclaim rebel districts in the central Syria city, the Syrian Observatory for Human Rights said.

Regime forces were backed by tanks, which pounded the neighbourhood, activists said.

Fresh violence also broke out Tuesday on the outskirts of Baba Amr, another strategic neighbourhood which had become a symbol of resistance to President Bashar al-Assad's regime before it was overrun by the army a year ago.

"Troops launched rockets from the Baath university into parts of Baba Amr," said the Observatory, which relies on a network of activists, doctors and lawyers for its reporting.

Like other educational and health facilities across Syria, the university has been used before as an army base, although students have continued to attend classes.

Fierce clashes meanwhile "raged" in Baba Amr, the Observatory added.

Once an opposition bastion, the army seized Baba Amr from rebel hands last year after a relentless, month-long bombing campaign on the neighbourhood.

Rebels two days ago launched a counter-offensive in a bid to retake Babr Amr, sparking heavy fighting during which the military launched artillery attacks and waves of air strikes.

Elsewhere in Syria, fresh battles broke out on the road linking Damascus to the airport, southeast of the capital on the edges of the Beit Sahem, Aqraba and Jaramana neighbourhoods, said the watchdog.

Rebels have for months being trying to seize control of the road leading to the airport, but have continually been repulsed by regime forces.

The road is strategic because it leads to the regime's main gateway to the world, and because it is near the Eastern Ghouta area of Damascus province, home to some of the rebels' better organised fighting forces.

In the capital itself, fighting broke out Tuesday in the eastern district of Jobar, whose outer edges are in rebel hands.

Syria's two-year conflict has left some 70,000 people dead, the UN says.

On Monday alone, at least 148 people were killed in violence across Syria, among them 65 rebel fighters, 42 soldiers and 41 civilians, said the Observatory.