A Lebanese man kidnapped in the border area with Syria was freed on Saturday, prompting the release of 11 other people who had been held in a string of retaliatory kidnaps.

Hussein Kamel Jaafar, a Shiite resident of an area near the northern Lebanese town of Arsal, was kidnapped last month and reportedly taken into Syria.

In response, members of his family took captive several local Sunnis, whose families also carried out retaliatory kidnappings.

"A delegation of Arsal residents returned from Syria at dawn this morning after receiving Hussein Kamel Jaafar," a security source told AFP.

"They paid a ransom of $150,000 to secure Jaafar's release," the source said.

Local television showed footage of Jaafar arriving in Arsal in the early hours of Saturday, and being received by officials.

"I was kidnapped by bandits and thieves, not the Free Syrian Army," Jaafar told LBC news, adding that his captors "beat me and tortured me."

In a statement, the Lebanese military confirmed the release of Jaafar and 11 other men who had been abducted in recent weeks, both Sunni and Shiite.

After Jaafar's kidnap, armed members of his family from Hermel and Baalbek kidnapped several Sunni residents of Arsal, security sources said, prompting additional counter-kidnaps of Shiite Lebanese.

Arsal is a majority Sunni Muslim town whose inhabitants generally support the revolt in neighbouring Syria.

Largely Shiite Hermel and Baalbek are strongholds of the Hezbollah organisation, which backs the Syrian regime of President Bashar al-Assad.

Lebanon is sharply divided over the war in Syria, which the United Nations says has killed at least 70,000 people since March 2011, and violence has spilled across the border on multiple occasions.

Four mortar rounds fired from Syria landed in Hermel in northeast Lebanon on Saturday, an AFP correspondent said.