The number-two of the al-Qaida group in Iraq Ayman al-Zawahiri on Friday called on Palestinians to reject a referendum imposed by the Palestinian President Mahmoud Abbas in a video tape aired on Al-Jazeera news channel.

Zawahiri said in the tape that he call upon the Palestinians to reject any referendum because Palestine is not for bargaining or bidding.

Palestine is a land of Islam and its liberation is the duty of every Muslim, he added.

Abbas stated two weeks ago at the beginning of a national dialogue that he would call for a popular referendum, only if the Palestinian factions, mainly ruling Islamic Resistance Movement (Hamas), fail to agree on a prisoners' document.

The prisoners' document calls for the establishment of an independent Palestinian state on the territories that were occupied by Israel in the 1967 Arab-Israeli war.

In the video tape, Zawahiri, however, didn't talk about the killing of Abu Musab al-Zarqawi, who was believed to be the top leader of the al-Qaida in Iraq.

Al-Zarqawi, the most wanted insurgent in Iraq, was killed on Wednesday evening along with his seven top aides by a U.S. air raid in their safe house in Hibhib, about 40 km northeast of Baghdad, according to official announcement.