Shaikh Saleh bin Humaid, a preacher at Makka's Grand Mosque, told worshippers before Friday prayers that those who killed at least 18 people, mostly expatriate Arabs, at a housing complex in Riyadh were seeking to sow strife among Muslims.

"Is the terrorism of Israel and the terrorism of those linked?" Humaid, who heads the kingdom's consultative Shura Council, asked in an address broadcast live on state television.

"Is the purpose to kill more Arabs and Muslims and create more violence and instability?"

"It is only inevitable to draw the comparison with the women and children who are being killed in Palestine and the homes that are being razed to the women and children who were killed in Riyadh while they were safe inside their homes."

The comparison of the militants to Israel, widely reviled in the Arab world, underlined the strength of recent rhetoric from the Saudi establishment against al-Qaida following a series of attacks in the kingdom and criticism from Riyadh's US allies that it was not cracking down hard enough.

Humaid urged everyone in Saudi Arabia - including security forces and media - to combat terror and radical ideology.

Saudi Arabia has come under intense pressure from the United States since the September 11 attacks two years ago to alter its religious and educational establishments, which some accuse of fomenting extremism and hatred towards non-Muslims.

Fifteen of the 19 plane hijackers involved in the attacks on Washington and New York were Saudis.