A convicted Basque terrorist is using the threat of hunger strike to blackmail a judge into throwing out a bid to extradite him back to Spain, a court in Belfast has heard.

A lawyer representing the Spanish authorities said a claim by Jose Ignacio de Juana Chaos, 54, that he will refuse food if he is returned to prison in Spain was not evidence that he will be subjected to inhumane treatment in custody.

De Juana Chaos, who has already served 21 years in a Spanish jail for his role in 25 murders, is fighting efforts to extradite him from Northern Ireland to face new charges of glorifying terrorism.

The Basque separatist, who has been living in Belfast for the last year, is wanted over the contents of a letter - alleged penned by him - that was read out at a rally at San Sebastian in August 2008.

Barrister Stephen Ritchie told judge Tom Burgess that the legal argument that de Juana Chaos would face likely death by hunger strike if was he put back behind bars in Spain to await trial did not provide sufficient grounds to reject the extradition bid.

"In effect what the defendant is saying to the court is 'I will probably go on hunger strike and I may die'," said Mr Ritchie.

"That sounds very much like blackmail. But it comes nowhere near reaching the threshold of proving he would face inhumane or degrading treatment (in a Spanish jail)."

The lawyer outlined the Spanish case for returning de Juana Chaos to its jurisdiction during closing submissions in the two-day hearing.

Judge Burgess said he would reserve judgment on the matter and announce his ruling at the nearest possible date.