Nick Griffin, the leader of the far-right British National party, appeared in Athens on Friday to pledge his support for Greece's neo-fascist organisation Golden Dawn.

Griffin, who was declared bankrupt last week, attended the Golden Dawn press conference to challenge the Greek government's crackdown on the extremist group in the European court of human rights.

Critics said the decision to share a platform with Golden Dawn indicated he was turning his back on any hope electoral success in the UK.

"This is further evidence that Nick Griffin and the BNP have abandoned their earlier attempt to appear as a more moderate and electorally appealing political party," said Matthew Goodwin, an expert in far-right politics from Nottingham University. "Instead, both Griffin and his party have indulged in open admiration of a neo-Nazi party that has been linked to murder and violent attacks against migrants."

Griffin was declared bankrupt last week following a dispute with a firm of solicitors over outstanding debts worth £120,000. It was the latest in a series of blows to the far-right organisation that has seen plummeting support at the ballot box and the departure of scores of key organisers.

Golden Dawn's leader, Nikos Michaloliakos, has been in pre-trial custody since the September murder of the leftwing rapper Pavlos Fyssas by a self-confessed party member. The killing prompted a government crackdown that unmasked the group as a violent paramilitary organisation.

Thirteen Golden Dawn MPs are either in detention, face charges, or have had their parliamentary immunity lifted as prosecutors build a case that its leadership was involved in attacks.

Michaloliakos has vehemently denied the charges and argued he is a political prisoner.

Griffin, who will defend his seat at the European parliament later this year, has previously expressed his "full solidarity with Greek patriots being persecuted by the system as a consequence of their fast growing support among ordinary Greeks".

At Friday's conference he said the current "pseudo-legal war" against Golden Dawn by the Greek government was "totally illegal" adding: "Long live freedom, victory to Golden Dawn … our time will come."

Goodwin said he was becoming "detached from political reality".

"Rather than rebuilding his movement for the European and local elections, he has chosen to build links with neo-Nazis, launch a cooking programme for his dwindling number of supporters and generally appearing as a rather odd character. Increasingly, he is becoming a comical rather than threatening figure in British politics".

A spokesman for the BNP said it was still committed to elections in the UK, adding that what had happened to Golden Dawn "was absolutely outrageous".