John Sopko, the US special inspector general for Afghanistan reconstruction, said on Wednesday his office would look into allegations that former Afghan President Ashraf Ghani took millions of dollars with him when he left the country.

Ghani has said he left Kabul to prevent bloodshed and denied reports he took large sums of money with him. But speculation has persisted, and Congress asked Sopko's team to get to the bottom of it.

“We haven’t proven that yet. We’re looking into that. Actually, the Oversight and Government Reform Committee has asked us to look into that,” Sopko told a House of Representatives subcommittee.

Ghani has been bitterly criticized for fleeing as the Taliban reached the outskirts of Kabul in August.

Sopko’s Office of the Special Inspector General for Afghanistan Reconstruction (SIGAR) has long been investigating fraud, waste and abuse during America’s massive state-building effort, which came to an ignoble end after 20 years with the Taliban takeover.

Sopko suggested to the House Foreign Affairs Committee subcommittee that oversees development aid that the failure of the US project shouldn’t have been a surprise, given rampant corruption and mismanagement.

“Corruption grew so pervasive that it ultimately threatened the security and reconstruction mission in Afghanistan,” he told the House panel.

The congressional hearing was one of a series looking at the chaotic US withdrawal and the path forward. “We can apply the lessons learned in other conflict zones,” Representative Joaquin Castro, the subcommittee’s Democratic chairman, said.

The United States and other countries have cut off almost all aid to Afghanistan.

“These are trying times for all of us who care about the future of the Afghan people, especially the Afghans that aided the US and its allies over the past 20 years,” Sopko said.

He said all of SIGAR’s staff - including locally employed Afghan staff - were safely evacuated from Kabul.