The money, part of the White House's request for $87 billion in supplemental spending on Iraq and Afghanistan, comes on top of at least $300 million that has already been spent on the weapons search, the officials said.

The budget figures for the weapons search are included in the classified part of the administration's supplemental appropriations request, and have not been made public. The size of the request suggests the White House is determined to keep searching for unconventional weapons or evidence that they were being developed under Mr. Hussein. The search so far has turned up no solid evidence that Iraq had chemical, biological or nuclear weapons when the American invasion began in March, according to administration officials.

Counting the money already spent, the total price tag for the search will approach $1 billion.

The money is intended specifically to pay for the activities of the Iraq Survey Group, made up of teams of troops and experts who are managed by the Pentagon but whose activities are coordinated by David Kay, a former United Nations weapons inspector who reports to the director of central intelligence, George J. Tenet.

Officials said the money for the Iraq Survey Group comes under the classified intelligence part of the Pentagon's budget request. A Pentagon spokesman declined to comment on the classified category.

The request for increased funding comes just as Mr. Kay is scheduled to brief Congress in closed sessions on Thursday on an interim report of the Iraq Survey Group's findings so far.

He is to testify before the House Permanent Select Committee on Intelligence, and the Senate Select Committee on Intelligence. The CIA is expected to publicly release a declassified statement based on Kay's testimony after the briefings, officials said.

CIA and other officials said last week that Kay's report would be inconclusive, suggesting that he will not say that he has found strong evidence of the existence of illegal weapons in Iraq.

Since the fall of the Hussein government, the failure to find evidence of illegal weapons has been a major political embarrassment for the Bush administration.

After the initial military-led effort to find such weapons came under fire, President Bush turned to the CIA to oversee an expanded search. In June, Tenet asked Kay to act as his personal adviser on the issue and to provide strategic advice to the weapons hunters.

Officials familiar with the request said that if the administration gets all the money it is seeking, it will provide funding for a staff of 1,400 for the Iraq Survey Group. It currently has more than 1,200 members.