Human Rights Watch urged Lebanon to rein in rising sectarian tensions fuelled as the civil war in neighbouring Syria spills across the border.

The US-based watchdog said Lebanese security forces need to better protect minority Alawites in the northern city of Tripoli, 18 miles from the Syrian border.

Alawites, a Shi'ite offshoot sect, are under increasing attack from Lebanese Sunnis who support Syrian rebels trying to topple President Bashar Assad's Alawite-dominated government.

Lebanon has struggled to cope with a massive influx of Syrian refugees and Lebanese factions loyal to Syria's warring sides have clashed along sectarian lines.

Lebanese Shi'ite group Hezbollah has played a critical role in recent victories by Assad loyalists in Syria, angering Sunnis at home.

The Lebanese government authorised the army to take temporary charge of security in Tripoli after recent deadly clashes.

Human Rights Watch said that Alawites had been beaten and stabbed, and the whole community had endured gun battles and mortar attacks over the past year.

It said the Beirut government's security plan for Tripoli was inadequate.

"There is no quick fix to the rampant violence in Tripoli," said the group's deputy Middle East director Joe Stork.

"But addressing the problem of impunity of gunmen is absolutely key."

nThe UN and Arab League's Syria envoy Lakhdar Brahimi met US and Russian delegations yesterday to try to agree which nations should be invited to peace talks next month.