Lebanon has sent troops to the port city of Tripoli after at least 10 people were killed in clashes linked to unrest across the border in Syria.

Security forces were deployed after the country´s Prime Minister Najib Mikati visited to try and stem the violence.

The clashes came after UN peace envoy Kofi Annan warned sectarian violence in Syria could spread across borders.

Recent weeks have seen increased clashes between armed Alawite groups and Sunni fighters in the city.

"The Lebanese army and internal security forces need to take all measures to stop the clashes in the city of Tripoli, without discrimination," a statement from Mr Mikati´s office said.

Armoured vehicles were seen on the streets of the city but no shots were fired, a Reuters report said.

Spilling over

Fighting was concentrated in Tripoli´s Bab al-Tebbaneh district, a mostly Sunni Muslim community, and the pro-Damascus Alawite Jabal Mohsen neighbourhood.

Although there have been on-off clashes between gunmen in neighbouring Tripoli districts, Saturday´s death toll is believed to be the highest in a single day.

The BBC´s Jim Muir, in Beirut, says that the fighting pits Sunni gunmen - who support the uprising in Syria - against Alawites, who back President Bashar al-Assad´s Alawite-dominated regime in Damascus.

These sectarian fault-lines run through the region and connect in Syria, fuelling the fear that the possibility of an all-out civil war in Syria could have dangerous repercussions for its neighbours.

"We are being targeted because we support the Syrian people," one Sunni gunman told Associated Press Television. "We are with you [Syrian people] and will not abandon you," he added.

On 14 May, five people were killed in similar clashes after a Sunni cleric, Shadi al-Moulawi, was arrested on terrorism charges. His supporters say he was held because he helped Syrian refugees.

In February, two died when supporters and opponents of Mr Assad clashed.

Community leaders in Lebanon have repeatedly warned of the possibility that the violence in Syria would spill over the border. Lebanon is already hosting thousands of Syrian refugees.

Last month, 11 Lebanese Shia Muslim pilgrims were abducted, reportedly by a Sunni rebel splinter group, in Syria.

On Friday, the leader of Lebanon´s Hezbollah movement, Sheikh Hassan Nasrallah, called for their release. (© BBC MMXII 06/03/12)