US authorities pursuing a sweeping fraud investigation suspect some 4,000 Iraqis of filing fraudulent applications for resettlement in the United States as refugees, and they are re-examining cases involving more than 104,000 others, according to State Department reports reviewed by Reuters.

More than 500 Iraqis already admitted as refugees have been implicated in the alleged fraud and could be deported or stripped of their US citizenship, according to one document sent to members of Congress. It said there was “no indication to date that any of these 500+ individuals have ties to terrorism.”

The probe – one of the biggest into refugee programme fraud in recent history – is fueling reservations among some in Joe Biden’s administration as they debate whether to create a similar programme to assist Afghan refugees as American troops withdraw after 20 years of war, US officials told Reuters.

The reports show the investigation is more far-reaching and serious than US officials have disclosed since announcing in January a 90-day freeze of the Iraqi “Direct Access” refugee programme. The suspension, which in April was extended indefinitely by the State Department, followed the unsealing of an indictment accusing three foreign nationals of fraud, records theft and money laundering.

A State Department spokesperson declined to comment on the scope of the investigation and internal government deliberations, but said the fraud scheme did not affect security vetting of refugees.

“The discovery, investigation, and prosecution of individuals involved in the scheme demonstrated the U.S. government’s commitment to ensuring the integrity of the programme while upholding our humanitarian tradition,” the spokesperson said. “Those who would seek to take advantage of America’s generosity in welcoming the most vulnerable people will be held accountable.”

The spokesperson did not give a timeline for the investigation, but said the agency would work “as quickly and thoroughly as possible” to complete the review and make any necessary security changes.

Sponsored by the late Senator Edward Kennedy, the “Direct Access” programme was authorised by Congress four years into the 2003-2011 US occupation of Iraq and the sectarian bloodletting it unleashed. The programme aimed to speed resettlement in the United States of Iraqis endangered by working for the US government.

Under pressure from lawmakers of both parties and advocacy groups, the Biden administration is considering a similar programme for Afghans facing Taliban retribution, according to a State Department official, a congressional aide and a lawmaker.

But there “are a lot of reservations” about expediting the resettlement of Afghans as refugees in the United States, said the State Department official, citing the problems with the Iraqi programme.

The official, who requested anonymity to discuss internal deliberations, referenced challenges to verifying employment history and other background information “in unstable environments.”

Representative Jason Crow, a former Army Ranger who founded a bipartisan group pressing Biden to evacuate at-risk Afghans, said State Department officials told him the problems with the Iraqi programme “have given people pause” about creating one for Afghans.