The extradition hearing for a Co Donegal man wanted by prosecutors in Northern Ireland over the murder of two UDR soldiers in Fermanagh in 1972 has heard claims that police in the UK attempted to fabricate photofit evidence using a picture taken from his house.

John Downey, 67, appeared before the High Court in Dublin on Monday to face the extradition hearing.

Downey's barrister Garnet Orange SC, said the claims emerged during disclosure proceedings at his trial for the IRA's Hyde Park bombing which collapsed in controversy four years ago.

Downey was detained on an unrelated matter in the Republic of Ireland last October under a European arrest warrant. Last year, Northern Ireland's Public Prosecution Service initiated extradition proceedings after determining it had sufficient evidence to charge him with the murders of Lance Corporal Alfred Johnston, 32, and Private James Eames, 33, in a car bomb attack in Enniskillen, Co Fermanagh.

The two Ulster Defence Regiment soldiers died when an IRA bomb exploded in a car they were checking on Irvinestown Road, Cherrymount, on August 25 1972.

In 2013, Downey was charged with murdering four Royal Household Cavalrymen in a bomb in London's Hyde Park in 1982.

He stood trial at the Old Bailey, but the case dramatically collapsed after it was revealed he had received a written assurance from former prime minister Tony Blair's government that he was not actively wanted by the authorities.

The letter was issued under the terms of the controversial On The Runs (OTRs) scheme.

Mr Downey has always denied any involvement in the Hyde Park attack.

During Monday's hearing, Mr Orange said there were "credible attempts" to "fabricate visual identification evidence" in relation to the 1982 offences.

The court was told that members of An Garda Siochana "unlawfully" removed pictures of Downey from his home and passed them to the authorities in the UK.

These pictures, Mr Orange said, were used to create an image of Downey as a suspect in the Hyde Park bombing.

Mr Orange said: "It appears from the information given to my client that the image in question was generated from a picture of my client which was taken from his house before 1982 in the course of the raid by the gardai."

During Monday's hearing, Mr Orange also claimed that gardai took his fingerprints "without legal justification" which were then sent to the UK authorities.

"That is a clear breach of his rights," he added.

"Gardai took his fingerprints without his consent, retained them without his consent or any legal justification."

Downey's barrister said his client is now subject to the extradition proceedings because of the same "catastrophic failure".

"The irony at this stage is that the very people who contributed to the failure are the very people who are bringing this application for extradition," he added.

"The UK authorities are having a second bite of the same cherry."

He also made an appeal to Ms Justice Aileen Donnelly to not proceed with the case until after March 29 when Brexit matters have been clarified.

Remy Farrell, barrister for the State, said however that Downey's counsel did not identify how his client would be impinged by Brexit.

Justice Donnelly said she will reserve judgment until March 1.