Both Russia and China have been loyal supporters of Mr. Assad but they also value their relationships with many other countries in the Arab world, so the Saudi king’s remarks amounted to a further sign that those relationships have suffered some damage.

“No matter how powerful, countries cannot rule the whole world,” the king said in his speech, as translated by Agence France-Presse. “The world is ruled by brains by justice, by morals and by fairness.”

His speech came as Mr. Assad’s forces continued a deadly assault on antigovernment resistance in the central city of Homs, where hundreds have been reported killed over the past week in what critics of Mr. Assad, including Saudi Arabia and other members of the Arab League, have called a bloodbath sanctified by the Russia-China veto. There were also large explosions reported in the northern Syrian city of Aleppo, one near a military intelligence office and another at a police headquarters. State media said 25 people were killed and 175 injured.

Earlier this week the six-nation Gulf Cooperation Council, of which Saudi Arabia is the largest member, expelled Syrian ambassadors from their capitals and recalled their own ambassadors from Damascus to protest what they called the “mass slaughter” of civilians in Homs and elsewhere by Mr. Assad’s forces.