Moscow warned last night that turmoil in Syria threatened to spill into Lebanon as the families of 11 Lebanese Shiite pilgrims abducted in northern Syria awaited their release.

"Considering history, the ethnic and religious make-up of the population, and the principles on which Lebanon's government is based, everything can have a very bad ending," the Russian foreign minister Sergei Lavrov said.

The Lebanese foreign minister Adnan Mansur said he expected the kidnapped pilgrims to be freed "within hours". Turkey and some Arab countries had helped to find the group, who were kidnapped on Tuesday near Aleppo while returning from a pilgrimage.

Mr Mansur did not say where the group had been found but accused "a splinter group of the armed Syrian opposition" of the kidnapping. The Free Syrian Army is a loosely knit group of rebels leading an insurgency against the regime of the president, Bashar Al Assad.

The country's exiled opposition group, the Syrian National Council, yesterday called on the FSA in a statement "to do everything they can to free the Lebanese brothers". It said it "condemns any kidnappings, assault or terrorising of our Lebanese brothers and demands their immediate release".

The FSA denied the group's responsibility. "The FSA does not believe in this methodology," said Mustafa Al Sheikh, who head's the FSA military council.

Saudi Arabia's ruler, King Abdullah, said his country was "deeply concerned" by the flare-up in Lebanon in a letter sent on Tuesday to the country's president, Michel Suleiman. He requested that the Lebanese president steer his country clear of Syria's unrest.

"Due to the gravity of the crisis and the possibility of it causing a sectarian strife in Lebanon and bringing it back to the shadow of the civil war, we are looking to your … attempts to interfere to end the crisis ... and keeping Lebanon away from foreign struggles especially with the Syrian crisis nearby," according to the letter, reported Lebanon's state news agency, SPA.

Meanwhile, armed opposition groups in Syria reportedly kidnapped three Iranian lorry drivers, Iran's charge d'affaires in Damascus, Mohammad Zeinali, said yesterday.

The release of the Lebanese Shiite pilgrims could help ease tensions in Lebanon, sparked by the violence in Syria, where the UN estimates more than 9,000 people have been killed as the conflict spirals toward civil war.

On the streets of Beirut, protests were held on Tuesday evening by family members of the abducted Shiites - the latest of several religious communities in Lebanon to demonstrate because of events linked to Syria.

To calm the protesters, who blocked roads and burnt tyres in Beirut's southern Shiite area, Hasan Nasrallah, leader the powerful Shiite movement Hizbollah, made a rare public plea.

Earlier this month, Sunnis in Tripoli staged anti-government demonstrations and waged gun battles against the Alawite minority, who from the same sect as Syria's ruling Al Assad family. That triggered more gun battles on Monday in Beirut between two Sunni groups divided over the Syrian uprising.

Unrest spilling into Lebanon, whose fractious religious sects fought a 15-year civil war that ended in 1990, has increasingly unsettled the international community.

Saudi Arabia and Qatar have reportedly increased financial support to Syrian rebels for purchasing arms.