The United States government has decided to halt monthly $335,000 payments to the Iraqi National Congress, the group headed by Ahmad Chalabi, an official with the group said on Monday.

Mr. Chalabi, a longtime exile leader and now a member of the Iraqi Governing Council, played a crucial role in persuading the administration that Saddam Hussein had to be removed from power. But he has since become a lightning rod for critics of the Bush administration, who say the United States relied on him too heavily for prewar intelligence that has since proved faulty.

Mr. Chalabi's group has received at least $27 million in United States financing in the past four years, the Iraqi National Congress official said. This includes $335,000 a month as part of a classified program through the Defense Intelligence Agency, since the summer of 2002, to help gather intelligence in Iraq. The official said his group had been told that financing will cease June 30, when occupation authorities are scheduled to turn over sovereignty to Iraqis.

Internal reviews by the United States government have found that much of the information provided as part of the classified program before American forces invaded Iraq last year was useless, misleading or even fabricated.