"A group of lions of Al-Qaeda in Iraq launched ... a new attack on the Jewish state by firing 10 Grad missiles from the Muslims' land in Lebanon against targets in the north of the Jewish state," it said.

"The brothers carried out the operation as planned and withdrew," said the statement, whose authenticity could not be confirmed.

The latest statement was the first claim of responsibility from Al-Qaeda for an attack on Israel.

"This laudable conquest came about by mujahedeen who applied the war oath of sheikh Osama bin Laden, emir of the Al-Qaeda network," it said, in reference to bin Laden's repeated assertions that Israelis should not enjoy security as long as Muslims do not.

"The worst is yet to come," warned the statement attributed to Al-Qaeda in Iraq, which is headed by Jordanian-born militant Abu Musab al-Zarqawi, Iraq's most-wanted man. It was signed by "spokesman Abu Musab al-Iraqi."

Israel on Wednesday carried out an air strike against a base of a Syrian-backed Palestinian group on the southern outskirts of Beirut in retaliation for cross-border rocket attacks on northern Israel.

Hours earlier, Katusha rockets were fired from southern Lebanon into northern Israel, without causing casualties. Two militants were slightly wounded in the air strike.

In Beirut, Lebanese Prime Minister Fuad Siniora declined to comment on the Al-Qaeda claim. Siniora has pledged an investigation "to find out who fired the missiles, pursue them and work to prevent the repetition of such acts".

The Shiite Hezbollah movement, which maintains fighters in southern Lebanon near the Israeli border, also refrained from comment.