Beirut - Syrian President Bashar Assad's forces have retaken a town on the Lebanese border as they press an offensive against rebels in a conflict that has now cost more than 100 000 lives, activists said on Wednesday.

The army took full control of Tel Kalakh, driving out insurgents and ending an unofficial truce under which it had allowed a small rebel presence to remain for several months.

The fall of Tel Kalakh, 3km from the border with Lebanon, marks another gain for Assad after the capture of the rebel stronghold of Qusair this month, and consolidates his control around the central city of Homs, which links Damascus to his Alawite heartland overlooking the Mediterranean coast.

Like Qusair, Tel Kalakh was used by rebels in the early stages of the conflict as a transit point for weapons and fighters smuggled into Syria to join the fight against Assad.

Pro-Assad websites showed video footage of soldiers patrolling the town in armoured cars and on foot.

"Terrorist groups infiltrated and terrorised the local people," an army officer said in the video. "In response to the request of the local people, the army entered Tel Kalakh to cleanse the area and restore security."

Urgent military aid

The British-based Syrian Observatory for Human Rights, a pro-opposition monitoring group, said rebels left the town on Tuesday, retreating towards the nearby Crusader fort of Crac des Chevaliers. Three rebels were killed as the army moved in.

Six months ago, Assad's opponents were challenging the president's grip on parts of Damascus, but are now under fierce military pressure there, while their supply lines from neighbouring Jordan and Lebanon have steadily been choked off.

In response to Assad's gains, achieved with the support of Lebanon's pro-Iranian Hezbollah fighters who spearheaded the assault on Qusair, Western and Arab nations pledged at the weekend to send urgent military aid to the rebels.

Hezbollah's involvement has highlighted the increasingly sectarian dynamic in the Syrian conflict. Hezbollah and Tehran back Assad, whose Alawite minority is an offshoot of Shi'ite Islam, while Sunni Muslim states such as Turkey, Saudi Arabia and Qatar have stepped up support for the mainly Sunni rebels.

Radical Sunni militants from abroad, some of them linked to al-Qaeda, are also coming in to fight alongside the rebels.

Jordan's King Abdullah said the war could ignite conflict across the Middle East unless global powers helped to convene peace talks soon.

Bleak prospects for peace talks

"It has become clear to all that the Syrian crisis may extend from being a civil war to a regional and sectarian conflict...the extent of which is unknown," the monarch told Asharq al-Awsat newspaper in an interview.

"It is time for a more serious Arab and international co-ordination to stop the deterioration of the Syrian crisis. The situation cannot wait any longer," he added.

But prospects for proposed "Geneva 2" peace talks look bleak. Talks on Tuesday between the United States and Russia, which support opposing sides in Syria, produced no agreement on who should attend the conference or when it should be held.

Saudi Arabia, which views Shi'ite Iran as its arch-rival, has stepped up aid to Syrian rebels in recent months, supplying anti-aircraft missiles among other weapons.

"Syria is facing a double-edged attack. It is facing genocide by the government and an invasion from outside the government," Saudi Foreign Minister Prince Saud al-Faisal said on Tuesday. "[It] is facing a massive flow of weapons to aid and abet that invasion and that genocide. This must end."

The Observatory, which monitors violence through a network of security and medical sources in Syria, said the death toll from two years of conflict had risen above 100 000 - making it by far the deadliest of the uprisings to have swept the region.

10 000 detained

It said the figure included 18 000 rebel fighters and about 40 000 soldiers and pro-Assad militiamen. But the true number of combatants killed was likely to be double that due to both sides' secrecy in reporting casualties, it said.

In addition to the casualties, it said, 10 000 people had been detained by pro-Assad forces and 2 500 soldiers and loyalist militiamen had been captured by the rebels.

The United Nations has put the death toll from the 27-month-old conflict at 93 000 by the end of April.

The violence has fuelled instability and sectarian tensions in Syria's neighbours, particularly Iraq and Lebanon.

At least 40 people were killed this week in the Lebanese city of Sidon in clashes between the army and gunmen loyal to a firebrand Sunni cleric who backs the Syrian rebels and has urged Sunnis to challenge Hezbollah's military might in Lebanon.

On Wednesday, unidentified attackers stabbed at least five passengers on a bus carrying Syrians in Beirut, security sources said. None of the victims was seriously wounded, they said.