Beirut (AFP) - Lebanon arrested Saturday a fugitive Sunni Muslim cleric wanted over deadly clashes with the army as he tried to flee the country, security sources told AFP.

"Lebanese authorities arrested Ahmad al-Assir this morning at the airport. He had changed his appearance and was trying to leave the country," a security source said.

Assir, who had shaved his beard, was trying to fly to Nigeria by way of Cairo, using a fake Palestinian travel document that had a valid visa, the security directorate added.

He had been on the run since June 2013, when he and some supporters fought a deadly battle with the army outside the southern city of Sidon.

The army seized his headquarters after 48 hours of clashes that killed 18 soldiers, but Assir was able to escape with several of his followers.

He has continued to issue audio statements while on the run, and various rumours circulated as to where in Lebanon he was hiding.

In 2014, prosecutors sought the death sentences for Assir and 53 others, including singer-turned-fundamentalist Fadel Shaker.

They were accused of having formed armed groups that attacked the army, killing officers and soldiers, and of having explosive materials, light and heavy weapons that they used against the army.

Assir, a native of Sidon, was virtually unknown politically before the outbreak of Syria's civil war in 2011.

He began making headlines after the conflict erupted by criticising Lebanon's powerful Shiite movement Hezbollah and its ally, Syrian President Bashar al-Assad.

Although he was born to a Shiite mother, his discourse was highly sectarian and he often accused Lebanon's army of failing to protect Sunnis and of being beholden to Hezbollah.

He encouraged his supporters to join Syria's mainly Sunni rebels and to rise up against Hezbollah.

Assir also grabbed headlines with media stunts, such as taking a group of his followers to the trendy winter ski resort of Faraya in early 2013.

The clashes between his supporters and the army erupted on June 24, 2013, after they opened fire on a military checkpoint.

The fighting, which centred on the Abra district in the eastern outskirts of Sidon, spread quickly, wounding dozens of civilians and paralysing much of the coastal city.

When the fighting was over, weapons including rocket launchers were found in Assir's headquarters complex, which included a mosque, several office buildings and apartment blocks.