Deputies voted by 304 to 16 in favour of the bill to ban the Batasuna party, which the Justice Minister, Angel Acebes, described as being part of a terrorist movement.

Those who shelter terrorists will be prosecuted - in Spain, our democracy is not willing to be forced into a corner or blackmailed by terrorists

Jose Maria Aznar

The bill will now go on to the Senate, where it is expected to be passed without amendments on 25 June.

The law would allow the Spanish Supreme Court to dissolve political parties which are considered to encourage or support terrorism.

Batasuna won 10% of the vote in last year's regional elections in the Basque region.

Opponents

The right-wing government of Prime Minister Jose Maria Aznar says that Batasuna, a coalition of pro-independence groups, is essentially a part of ETA.

ETA wants full independence

"Those who shelter terrorists will be prosecuted," said Mr Aznar during a visit to Brussels.

"In Spain, our democracy is not willing to be forced into a corner or blackmailed by terrorists."

The bill was supported by the opposition Socialist Party, but is opposed by left-wing groups and moderate Basque nationalists.

Opponents argue that the bill will only unite radical nationalists and make them more powerful.

And on Sunday, 350 Catholic priests signed an open letter in support of Basque bishops who said the measures would lead to more violence and division in the region.

Batasuna means "United" in Basque, and was formed soon after the end of the Franco dictatorship in 1975.

It was originally known as Herri Batasuna, or "People United".

Batasuna reached its highpoint in regional elections in January 1999 when it polled just under 15% of the vote.

But it lost ground after ETA ended its ceasefire a year later and renewed its bombing campaign.