Thirty-five illegal migrants were reported to be free in the north-east last night after immigration officials at Aberdeen Airport granted them emergency admission to the UK.
It is understood 37 new arrivals from Bolivia in South America were released on condition they returned the following day to have immigration papers processed.
But only two came back and both were allowed to stay.
One MSP last night called for the “fullest possible inquiry” into what happened.
But the UK Border Agency downplayed it, claiming its officials had checked the names of those involved against their “watch-lists”.
It was reported that 42 Bolivian men and women arrived at Aberdeen Airport last week from Amsterdam.
Five were refused admission straight away due to problems with their papers.
It is believed there was no room to keep the other 37 because almost 40 people were already being held from another flight.
Grampian Police yesterday confirmed they were called due to the high number involved but said it was left in the hands of the agency.
The agency would not confirm whether it was actively seeking those missing.
North-east Tory MSP Alex Johnstone called the circumstances “astonishing”.
He said: “The situation appears to be a deliberate attempt to flood the facilities at Aberdeen Airport. And somebody somewhere surely must have been a bit naive to release so many people on the condition they come back.
“We need a proper inquiry so Aberdeen Airport is not seen as a soft touch.”
And Sir Andrew Green, spokesman for Migrationwatch UK, claimed the arrival en masse by the visitors was a deliberate ploy.
A spokesman for the UK Border Agency said: “These individuals were checked against our watch-lists before being allowed to enter the UK. We are reviewing our contingency arrangements at Aberdeen Airport and are working with Grampian Police to further strengthen procedures at the port. We have increased staff at our ports by nearly 35% since 2005.”