UNITED NATIONS, 28 October — The chief UN weapons inspector for Iraq, Hans Blix, could hold the key to bridging differences in the Security Council over a US draft resolution, diplomats said as negotiations moved to the endgame.

Blix is to brief the Council today, the start of what US Secretary of State Colin Powell has said will be make-or-break week for efforts to unite the 15 members behind a resolution giving Iraq a last chance to accept a tough new inspection regime. The five veto-carrying permanent members are split into two camps over proposals to reinforce the powers of the inspectors and to threaten Iraq with military force if it fails to cooperate.

While few diplomats believe that France, Russia or China would veto the US-British proposals, the draft still needs nine yes votes to be adopted, and the 10 non-permanent members have had little opportunity so far to enter the negotiations.

They could be persuaded by what they hear from Blix, a highly respected former foreign minister of Sweden who came out of retirement to head the UN Monitoring, Verification and Inspection Commission (UNMOVIC) after the Council set it up in December 1999.

Blix has had several meetings this year with senior Iraqi officials, most recently four weeks ago in Vienna, when he met Amir El-Sadi, an aide to President Saddam Hussein, and agreed on arrangements for starting work in Iraq.

Blix previously ran the International Atomic Energy Agency (IAEA), which is charged with supervising the dismantling of Iraq’s nuclear weapons program while UNMOVIC eliminates its chemical and biological weapons and long-range missiles. His successor at the IAEA, Mohammed El-Baradei, is due to brief the Council with him.

"The tendency among all Council members is to let Blix and El-Baradei be the arbiters of this," a diplomat from one of the permanent members said. "What the elected members will want to hear is, do these proposals help or hinder you?" he added.

Another diplomat said: "Whatever Blix and El-Baradei want we will agree to."

Several Council members have suggested that the Council should limit itself to endorsing the arrangements agreed in Vienna, set out in a 20-paragraph letter to the Iraqis on Oct. 8, rather than thrusting new powers upon the inspectors.

The US proposals would originally have allowed the United States to put its own people on an inspection team, provide armed escorts for them and to take Iraqi scientists or officials and their families out of the country for interview. Under pressure from France and Russia, the United States diluted the proposals, giving UNMOVIC and the IAEA discretion to use their powers.

If the briefing with Blix and El-Baradei does help resolve differences over the inspectors’ powers, it could create the mood for consensus also on the other major disagreement. That is a US proposal to declare Iraq "in material breach" of its obligations under Resolution 687, defining the terms of the cease-fire which ended the 1990-1991 Gulf War, and threatening "serious consequences" for its failure to cooperate with UN arms inspectors.