BEIRUT, Dec. 29 -- Commander of the United Nations Interim Force in Lebanon (UNIFIL) General Paolo Serra described the firing of 2 rockets from Lebanon towards Israel on Sunday as a very serious incident aimed at undermining the stability in the region.

Two Grad type 107 mm missiles fired from southern Lebanon towards Israel missed their target and exploded on Lebanese territory on Sunday.

A security source told Xinhua that the rockets were launched from the Arkoub area in the vicinity of the Kfarshouba village, but landed on a farm on Lebanese side of border with Israel, causing material damages.

The Israeli army retaliated by firing over 20 shells at the rocket launched area.

The UNIFIL contacted the Lebanese and Israeli sides, urging them to exercise restraint and determine the details of Sunday's incident with respective armies.

The UNIFIL commander said in a statement "this is a very serious incident and is clearly directed at undermining stability in the area," adding "UNIFIL's first imperative is to ensure no further escalation of the situation".

Lebanese army and UNIFIL forces carried out patrols in the area after the exchange of fire and the Army Command later announced that its units discovered four wooden rocket launchers used in the attack in the Wadi al-Khraybeh region in the Hasbaya district.

Tension has spiked on the border since Lebanese troops gunned down an Israeli soldier driving near the frontier on December 16.

Last week, the Lebanese militant Hezbollah party said one of its top leaders was killed near Beirut and blamed Israel for his murder, a charge denied by Israel, which warned against any retaliation.

UNIFIL troops were deployed along the border following the 34- day war in 2006 according to the Security Council Resolution 1701.