A campsite in Lebanon's Bekaa Valley
A campsite in Lebanon's Bekaa ValleyAFP/File

The United Nations Secretary General expressed concern on Monday over the sectarian violence in Lebanon, which has intensified in recent days in the wake of the civil war in Syria.

Al Arabiya reported that at least 20 followers of a radical Islamist cleric were found dead in a mosque complex in the southern town of Sidon, following deadly clashes with the Lebanese Army.

The army has taken control of a mosque complex, saying it has lost 12 soldiers in less than 24 hours of clashes. The Islamists were holed up inside the mosque, where radical cleric Ahmad Al-Assir gives his Friday sermons.

The fighting began on Sunday when Assir loyalists flared up violence, the army said in a statement cited by Al Arabiya.

The controversial Sunni sheikh called on his supporters last week to fire on apartments in Abra that he says house members of the Hizbullah terror group.

Abra is home to a mosque where Assir leads the main weekly prayers on Fridays. The sheikh believes Hizbullah uses the Abra apartments to keep him under surveillance.

Two months ago, Sheikh Assir lashed out at Hizbullah for helping Syrian President Bashar al-Assad’s forces fight the predominately Sunni opposition in the country, announcing the formation of “Free Resistance Brigades” to fight Hizbullah in Syria.

He said it was “a religious duty” for his Sunni followers to join the fight against Hizbullah and the Syrian regime.

It was later reported that Lebanese youth were responding to Assir’s call and were signing up for “armed Jihad in Syria.”

Meanwhile, reported AFP, UN chief Ban Ki-moon on Monday appealed to Lebanon’s armed forces to remain loyal to President Michel Sleiman as sectarian tensions fuelled by the Syrian conflict mounted.

Ban is following events in Lebanon with “deep concern,” said UN deputy spokesman Eduardo del Buey.

“He condemns the attacks on the Lebanese Armed Forces, which have led to serious losses in the army,” said del Buey, according to AFP.

Ban “stresses that all in Lebanon should fully respect the authority of the state and its institutions under the leadership of President Sleiman, in particular the Lebanese Armed Forces whose role is essential to protect all Lebanese.”

Syria-related tensions have soared in Lebanon, deepening sectarian rifts between Sunnis and Shiites.

Shiite Hizbullah openly supports Assad's regime and fights along his forces, while the Sunni-dominated opposition backs the rebels fighting it. The Syrian civil war has spilled into Lebanon on more than one occasion.

Lebanon's army recently warned it will hit back against any new attacks from Syria, after a helicopter gunship struck an eastern town.

Sleiman recently cautioned Hizbullah over its fighting alongside regime troops in neighboring Syria.

“The resistance is more noble and more important than anything, and should not get bogged down in the sands of dissension, whether in Syria or Lebanon,” he said in a statement, referring to Hizbullah’s strong stance against Israel.

The Gulf Cooperation Council (GCC) has announced that it will take action against Hizbullah loyalists living in the GCC countries because of the group’s support for Assad.

One of the Gulf states, Bahrain, recently became the first Arab country to blacklist Hizbullah as a terrorist organization and later banned opposition groups from having contact with the organization.