UN chief Ban Ki-moon is following the events in Lebanon with "deep concern," said UN deputy spokesman Eduardo del Buey after over a dozen Lebanese troops were killed as they battled followers of a radical Takfiri sheikh for two days.

"He condemns the attacks on the Lebanese armed forces, which have led to serious losses in the army," AFP quoted del Buey as saying.

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."

The UN said "the international community remains united in its support for Lebanon's sovereignty, security and stability."

"The secretary general reminds all concerned in Lebanon of their responsibility to avoid conflict and uphold the principles of mutual respect and coexistence in order to preserve Lebanon's national unity."