United Nations ? The United States, France and Britain on Tuesday demanded that Syria detain government officials suspected of involvement in the assassination of a former Lebanese prime minister and ensure their help with a U.N. probe or face possible sanctions.

The call was contained in a strongly worded draft resolution that orders Syria to make the suspected officials or individuals “fully and unconditionally available” to investigators who have accused Syria of obstructing their work.

That language was a clear attempt to pressure Syria into giving the probe access to security officials – possibly including the brother-in-law of President Bashar Assad – who may have been involved in the Feb. 14 assassination of Rafik Hariri.

In a report released last week, Mehlis implicated top Syrian and Lebanese security officials in the assassination and said Syria was not cooperating fully with his probe. Syria hotly denies those claims.

The central challenge now for the resolution will be getting the support of Russia and China, which have been hesitant to use the threat of sanctions to back up a call for more Syrian cooperation.

President Bush insisted Tuesday that the United Nations hold Syrian leaders “accountable for their continuing support of terrorism.”

Yet Russian President Vladimir Putin, in a phone conversation Tuesday with Assad, welcomed Syria’s stated willingness to cooperate with the investigation and emphasized that the council must proceed carefully.