Immigration inspectors at US ports of entry sometimes have no choice but to hand back stolen or forged travel documents to those using them - so the visitors can leave the country, reports UPI.
The procedure, acknowledged by senior Homeland Security officials as happening "very rarely", is one of series of weaknesses in the US visa waiver programme identified by the Department of Homeland Security's Inspector General Clarke Kent Ervin in a report presented to Congress.
"Many countries will not allow people to enter without a passport," Ervin explained.
He said that when immigration inspectors found people using stolen, forged or altered passports, they often had no choice but to allow them to use the documents to return to their country of departure.
"It does happen," confirmed Department of Homeland Security Assistant Secretary for Policy and Planning Stewart Verdery.
"But it happens very rarely and when it does, we give the passport to the airline, not to the traveller," he added.
Under the visa waiver programme, the US has reciprocal arrangements with 27 countries, whose nationals are allowed to enter the country without a visa for up to 90 days for business or pleasure.
{{/usCountry}}Under the visa waiver programme, the US has reciprocal arrangements with 27 countries, whose nationals are allowed to enter the country without a visa for up to 90 days for business or pleasure.
{{/usCountry}}Critics say the programme is a loophole in US security - pointing to the fact that both Briton Richard Reid - the so-called shoe bomber who attempted to down an American Airlines flight from Paris by igniting explosives hidden in his shoes - and Zacarias Moussaoui - accused of being the 20th 9/11 hijacker - used the exemption to enter the US.
Charles Showalter, president of the National Homeland Security Council, a labour union that represents 18,000 immigration personnel in the department, said the procedure his members followed was that laid down by the Department of Homeland Security.
He said that cases of so-called "non-escorted removal" were different from full deportation. If the US attorney declined prosecution, he said, the traveller was put back on a plane. The forged or stolen documents were given to the airline crew.
"At some point before landing," he said, "those documents will be returned, so that the person can use them to re-enter the country they came from."