Republicans on the House Oversight Committee are calling for a briefing from the Special Inspector General for Afghanistan Reconstruction’s (SIGAR), claiming that the Biden administration has been obstructing SIGAR's investigations of the U.S. withdrawal from Afghanistan in August 2021.

A letter to Special Inspector General John Sopko from the committee's ranking member Rep. James Comer, R-Ky., and National Security subcommittee ranking member Rep. Glenn Grothman, R-Wis., noted that SIGAR had previously told the Oversight Committee that the administration has failed to turn over information necessary for reports SIGAR is working on.

"Historically, State and USAID [United States Agency for International Development] have honored SIGAR’s mission," the letter said. "But since the Biden Administration’s botched Afghanistan withdrawal—which is in desperate need of oversight— State and USAID have denied travel, delayed, obstructed, and even questioned SIGAR’s jurisdictional authority. The Biden Administration’s obstruction directly violates the National Defense Authorization Act for FY 2008 and the Inspector General Act of 1978, as amended, which both require agencies to provide Inspectors General information or assistance."

SIGAR has been working on five reports to fulfill a request from the Oversight Committee to look into what caused the "rapid collapse of Afghanistan" and the impacts of the U.S. withdrawal.

A State Department spokesperson told Fox News that "some of the allegations are simply false."

"The State Department has provided SIGAR written responses to dozens of questions, as well as thousands of pages of responsive documents, analyses, and spreadsheets describing dozens of programs that were part of the U.S. government’s reconstruction effort in Afghanistan, despite the fact that the United States stopped providing assistance for the purpose of the reconstruction of Afghanistan following the Taliban takeover in August 2021," the spokesperson said.

A spokesperson for USAID told Fox News that the U.S. stopped giving assistance for Afghanistan reconstruction after the Taliban took over in August 2021.

"Nonetheless, since August, USAID has continued to cooperate and provide information to SIGAR, with upwards of 25 evaluations, audits and other engagements," the spokesperson said. "We’ve provided hundreds of pages of analysis, responsive documents, and spreadsheets, and we will continue to do so for any requests that fall under SIGAR’s statutory jurisdiction."

The letter from the House Republicans said that the State Department and USAID "have refused to provide basic information relevant to SIGAR’s audit concerning efforts to ensure that ongoing programs supporting the people of Afghanistan do not result in the illegal transfer of U.S. taxpayer funds to the Taliban or Haqqani Network." The Republicans also recalled that according to SIGAR, a State department official said department employees were told not to speak to SIGAR without being given clearance by the department's legal counsel.

The United States stopped providing assistance for the purpose of the reconstruction of Afghanistan following the Taliban takeover in August 2021. Nonetheless, since August, USAID has continued to cooperate and provide information to SIGAR, with upwards of 25 evaluations, audits and other engagements. We’ve provided hundreds of pages of analysis, responsive documents, and spreadsheets, and we will continue to do so for any requests that fall under SIGAR’s statutory jurisdiction.

"The Biden Administration’s obstruction of your investigations is unprecedented, matching the unprecedented Afghanistan withdrawal," the letter said. "If the Biden Administration does not begin cooperation with SIGAR’s requests, SIGAR will not be able to provide Congress with its independent, whole-of-government assessment of U.S. engagements in Afghanistan."

The lawmakers noted that the U.S. has spent more than $1.1 billion on humanitarian aid to the people of Afghanistan since the withdrawal, and that SIGAR has to look into any possible "waste, fraud, and abuse" as well as whether the Taliban had access to it.

"The lack of cooperation from the Biden Administration raises serious questions," the letter said. "What do they have to hide? Are funds being given to the Taliban? What is being done to assist women and girls? How is the U.S. engaging with the U.N. and other multilateral organizations on these matters."

The lawmakers called for the briefing to take place by November 1, at the latest. A SIGAR spokesperson indicated to Fox News that this will happen.

"We always comply with requests from committee chairmen and ranking members, and will do so in this case," the spokesperson said. "We look forward to briefing the committee."