A number of Polish citizens have been extradited from Northern Ireland in a secret operation.
Polish authorities, working with the PSNI, flew into Belfast on Monday, detained three of their fellow citizens living here and then flew out of the province yesterday.
The exact details of the operation are not yet known, but it is understood the Polish nationals could be wanted in connection with serious crimes in their home country.
Both the PSNI and the Polish Embassy in London confirmed the extradition operation to the Belfast Telegraph yesterday.
The arrests were undertaken as part of a European arrest warrant - an agreement within EU member states to extradite citizens found living in another country.
It applies to people wanted in connection with a criminal prosecution or prison sentence, and is only issued for offences carrying a penalty of 12 months or more.
On Monday a Polish military plane was chartered to George Best Belfast City Airport, where it remained overnight.
The PSNI's Extradition Unit, based at Knocknagoney, apprehended the three Polish nationals and held them until the Polish authorities arrived.
Officers then handed them over to their Polish counterparts and they were flown back to the eastern European country yesterday morning.
It was originally believed that up to 19 men were arrested in the clandestine operation, but the PSNI yesterday said the true figure was three.
A police spokeswoman said: "The PSNI can confirm that it assisted in the extradition of three Polish nationals as part of the execution of three separate European arrest warrants."
The Polish Embassy also confirmed the arrest operation took place.
"The plane was hired by the Polish police and the arrested Polish citizens were handed over by the Northern Ireland police," a spokesman said.
Both the Polish Embassy and the PSNI said they could not comment on the nature of the arrest warrants.