Saudi King Abdullah said on Friday that world confidence in the United Nations had been shaken after the world body failed to adopt a resolution against the Syrian regime's deadly crackdown on protests.

"We all used to take pride in the United Nations which used to bring us together and not divide us... but what took place does not augur well as world confidence in the United Nations has undoubtedly been shaken," King Abdullah said in a short televised speech.

"We are going through scary days and unfortunately what happened at the United Nations is absolutely regrettable," the Saudi king said.

King Abdullah was alluding to the blocking by Russia and China last Saturday of a UN Security Council resolution condemning the crackdown by President Bashar Al-Assad's regime.

"No matter how powerful, countries cannot rule the whole world," he said. "The world is ruled by brains, by justice, by morals and by fairness."

On Tuesday, the six Gulf states decided to expel Syrian envoys and withdraw their own over the "mass slaughter" of civilians.

Regional kingpin Saudi Arabia called on Monday for "critical measures" to be taken on Syria, warning of an impending "humanitarian disaster".

Human rights groups estimate that more than 6,000 people have died in Syria since protests erupted in March last year.