Gunmen have kidnapped 13 men from Syria's Alawite minority as they crossed into northern Lebanon, residents and security sources said.

Residents of Lebanon's northern border town of Wadi Khaled said gunmen attacked a bus carrying the men who came to Lebanon for work on Monday, beating the driver and kidnapping 13 Alawites.

They said the gunmen would release their hostages when a Lebanese Sunni man named Mohammed Hussein al-Ahmad, who residents say is being held by Syrian forces, was freed. 

A security source said Lebanon's armed forces sent patrols to the northern border area to look for the Syrian hostages. 

Lebanon's frontier has increasingly been drawn into violence from neighbouring Syria's civil war, now in its third year.

Sectarian tensions have been on the rise in both countries, with Sunni Muslims in Lebanon supporting the largely Sunni revolt against president Bashar al-Assad in Syria.

Shia and other minorities have backed Assad, himself from the Alawite sect that is an offshoot of Shia Islam.

The Lebanese-Syrian border has grown increasingly tense with battles raging close to the frontier. Syrian forces have threatened to increase shelling on Lebanon's border areas due to the presence of rebel groups there.

Source: Reuters