U.S. intelligence officials are expressing growing concerns that Pakistan is holding back valuable intelligence data obtained from captured No. 2 Taliban leader, Mullah Abdul Ghani Baradar.

Mullah Baradar, who was captured in January, is the military deputy to Taliban leader Mullah Omar and he is considered the most important terrorist to be detained since Khalid Shaikh Mohammed was caught in 2003.

Senior U.S. intelligence officials in the last week told The Washington Times that recent interrogation sessions with Mullah Baradar yielded very little actionable intelligence. Instead the sessions provided "atmospheric intelligence" that is of limited value, such as the history of the Pashtun tribal regions in Pakistan and Afghanistan.

Mullah Baradar, a key operational commander, is believed to know a wide range of information on the insurgency, from the Afghan Taliban's funding network to the identities of sleeper cells, agents and financiers in Europe and the west.

"He is talking about the general dynamics of the tribes," said a senior U.S. intelligence official in a position to know. "But he is not giving us anything on the locations of senior Taliban officials. He is not telling us about bank accounts; he is not talking about the donor support base; what the Taliban's capabilities are; or who in the [Pakistani Inter-Services Intelligence service] the Taliban is working with."

Officials interviewed spoke on condition of anonymity because of the sensitivity of the information.

A senior counterterrorism official sought to dispel any notion that Mullah Baradar has not provided useful information. This official said Mullah Baradar would not know at this point the locations of senior Taliban figures because he has been in custody for so long.

"It's simply incorrect to say that Baradar isn't providing anything useful," this official said. "If people are claiming that his questioning isn't yielding results because he isn't disclosing where the Taliban's top leadership is today, it's worth recalling that he's been in custody for months."

The official, however, did not directly address the question of whether Pakistan is withholding information obtained from the captured Taliban leader.

The Pakistanis captured Mullah Baradar in January outside of Karachi, Pakistan, using intelligence developed in part by the CIA. He is now in the custody of the ISI. U.S. intelligence officials said at the time that the capture was a major setback for Afghanistan's Taliban-led insurgency.

Mullah Baradar was responsible for rebuilding the Taliban, which has an estimated 20,000 fighters.

His capture triggered optimism inside the U.S. government that valuable intelligence on Taliban military operations, funding and strategy would be disclosed from interrogations. It was also hoped that the capture of the senior leader would boost Afghan and allied efforts to win over some Taliban insurgents to support the central government in Kabul.

The ISI historically supported the Taliban throughout the 1990s, viewing it as a counter to what they regarded as an Indian-supported Northern Alliance. Islamabad was one of the last governments to have full diplomatic relations with the Islamist militia when it ruled Afghanistan before the Sept. 11, 2001, attacks.

The United States and Pakistan have been uneasy allies against the Taliban since after the Sept. 11 attacks. The country has also been notoriously protective of its most valued prisoners.

The Pakistanis continue to prevent U.S. intelligence officials from questioning directly Abdul Qadeer Khan, the Pakistani physicist who helped establish Pakistan's nuclear arms program and then covertly sold nuclear weapons know-how and goods to North Korea, Libya and Iran.

Nadeem Kiani, a spokesman for Pakistan's embassy in Washington said, "It is a continuing process and we are interrogating him. We are following the leads. Our impression is that the United States side is also satisfied with the information they are getting from him."

The Pakistanis began providing regular access to Mr. Baradar in April, some four months after he was captured. A senior intelligence official said that it took two weeks after his capture before U.S. interrogators had the chance to pose direct questions to the Taliban deputy.

Officials said the delays may have been due in part to Pakistani ISI efforts to first confirm his identity after the capture. Nonetheless in February, the high court of Lahore ruled that Mullah Baradar may not be extradited to the United States.

One senior U.S. intelligence official said that he was concerned that the ISI may be interested in using Mullah Baradar to broker a peace deal with the Afghan Taliban, in preparation for the time in 2011 when U.S. forces are set to begin withdrawing from Afghanistan.

"The Pakistanis have every incentive to cut a deal with him, and he has every incentive to shut up," he said.

David Barno, a retired Army lieutenant general who commanded coalition forces in Afghanistan from 2003 to 2005 said, "Baradar is certainly a guy who would have great deal of detail on the inner workings of the Taliban. I tend to think the reporting that Baradar has served as an interlocutor between the Taliban and potentially Karzai's government on reconciliation is accurate."

Gen. Barno, who is now a senior adviser and fellow at the Center for a New American Security, said "Pakistan's interests in Baradar and the U.S. interests in Baradar may not be identical. Pakistan may see some utility in Baradar's relationships and influence, looking to the day after the United States is gone."