MOSCOW — Russia could abandon support for Syrian President Bashar al-Assad if it learned that he was not committed to handing over control of his chemical weapons arsenal, the chief of staff for President Vladimir Putin suggested on Saturday.

But Sergei Ivanov also reiterated Russia's long-standing opposition to western military intervention in Syria, saying that such action would only aid militants linked to al-Qaida.

"In the event of external military interference the opposition . . . would entirely lose interest in negotiations, considering that the U.S. would bomb the regime to its foundations as in Libya, giving them an easy path to victory," Ivanov said in comments reported by Russian media to a Stockholm conference organized by the British-based International Institute for Strategic Studies.

He said that Russia expected to know the whereabouts of all Assad's chemical weapons within a week, although it would take two to three months to decide how long would be required to eliminate them.

"I'm talking theoretically and hypothetically, but if we became sure that Assad is cheating, we could change our position," Sergei Ivanov said.