The top American diplomat for Pakistan, Richard C. Holbrooke, said that he would give a boost to efforts to trace the sources of financing for the Taliban insurgency, with special scrutiny of private donations reported by New York Times.

Mr. Holbrooke said that private donors, including some from Persian Gulf countries, were increasingly believed to be a far more important source of money for the Taliban than even the opium trade, which the United Nations estimates to be about $300 million a year. An American official responsible for Afghanistan said Friday that the opium money was believed to make up less than half of Taliban financing.

“In the past there was a kind of a feeling that the money all came from drugs in Afghanistan,” Mr. Holbrooke said. “That is simply not true.” Although Hillary Clinton has accepted “incoherent dealings” of US with Pakistan over the past 30 years.

Identifying the sources of money for the Taliban has been one of the most elusive goals for the United States since Sept. 11, 2001, but the task is central to the American war effort in Afghanistan, and to fighting militancy in Pakistan. But American officials have had limited success.

“We want to focus on where the money really comes from,” Mr. Holbrooke said. “I will be adding a member of the Treasury Department to my staff within two weeks so we can focus more heavily on this area.”

American intelligence officials have expressed concerns about financing for terrorism from gulf countries in the past, but Mr. Holbrooke’s remarks indicate that the United States may now seek to put more pressure on the countries to stanch the flow of money.