Home Secretary John Reid has hailed a new EU deal which could ease the pressure on UK prisons.
An accord in Brussels means that in future EU member states will be obliged to accept back their own nationals who have been convicted of crimes and given prison terms in other countries.
If the new rule applied today the Government could enforce the return to their own countries of 2,432 foreign nationals from other EU states currently in jail in England and Wales.
Equally, the UK could be expected to take back 840 Britons now serving sentences elsewhere in the EU.
Although the new requirement is not retroactive, and will not come into force for two years, UK officials expect the balance to remain in favour of reducing the domestic prison population.
"This deal is an excellent result," said Mr Reid. "It will provide significant improvements to existing prisoner transfer arrangements. It will create for the first time an obligation for a state to accept back its own nationals, something which the UK has constantly supported."
At the moment a prisoner's consent is required before transfer can be sought back to the country of origin. Even then the prisoner's own country can take up to two years to consider such a request and does not have to agree. Under the new rules no prisoner consent is needed, and his or her country has no choice but to comply with a request for transfer within three months.
Mr Reid said the new deal would considerably speed up the whole process: "This is another step forward in dealing with foreign national prisoners, and is something that is very important. We have constantly pushed for it."
Poland, which currently has 278 nationals serving sentences in jails in England and Wales, was the only country given a five-year delay before having to comply with the new rules.
The prisoner transfer agreement still requires formal endorsement by national EU scrutiny authorities in some countries before taking effect, an EU official said.
