Batasuna has been banned in and blacklisted in the US

The decision, which was made at the request of the Spanish Government, took effect on Thursday when the list was published during a meeting of EU interior ministers in Luxembourg.

Inclusion on the list obliges all EU countries to co-operate with officials investigating of prosecuting the party.

Batasuna, which is regarded as the political wing of the separatist organisation ETA, has already been banned by the Spanish Supreme Court.

Last month it was put on a United States blacklist of terror groups.

News of the ban coincided with reports that ETA had claimed responsibility for a car bomb last week in northern Spain which killed two policemen.

'Broadest assistance'

The EU list was drawn up after the 11 September attacks on the US, and includes groups and individuals believed to be linked to terrorism.

It requires all member states to give the "broadest possible assistance" to police and prosecutors working to prevent terrorist acts.

But it leaves decisions on whether or not to freeze an organisation's assets up to individual governments.

ETA first emerged in the 1960s as a student resistance movement bitterly opposed to General Franco's repressive military dictatorship.