Legal action is being considered by families of the Bloody Sunday victims over the lack of progress in the PSNI investigation into the 13 deaths, after it emerged that none of the paratroopers involved have been interviewed yet.

The police probe was pledged after the publication of the Saville Inquiry in 2010 which found that the civil rights demonstrators shot dead by British soldiers in Londonderry in 1972 were innocent.

Lord Saville’s probe, which took 12 years to complete costing nearly £200million, found that the victims had been shot without justification by the members of the Parachute Regiment.

He then apologised to the victims’ families, assuring them that the deaths would be investigated by the police.

In July, Chief Constable Matt Baggott revealed a PSNI murder investigation would take place lasting four years, with 30 skilled officers involved.

However, over two years on from the lengthy inquiry’s end, there have been no arrests – and not one interview carried out with a soldier.

UTV has seen a letter written by a senior PSNI Serious Crime branch detective acknowledging this.

The Bloody Sunday families are angry – their lawyers are considering legal action saying the lack of progress in the police investigation undermines the rule of law.

Peter Madden, of Madden & Finucane Solicitors, said: “It is staggering that almost two and a half years since Lord Saville delivered his report and the Prime Minister stated unequivocally in Parliament that all of the deceased and injured were shot without justification, that the Police Service of Northern Ireland has failed to take any reasonable steps to progress the prosecutions of those responsible.”

In January 2011, detailed submissions were forwarded to the Public Prosecution Service (PPS) in Belfast by the law firm seeking prosecutions.

Submissions were also forwarded to the Crown Prosecution Service in London in relation to when the Bloody Sunday Inquiry took evidence from witnesses there.

The following month, in February 2011, Madden & Finucane said the PPS confirmed that the matter had been referred to the PSNI to commence the probe.

Mr Madden continued: “We will be considering all legal remedies available to the families in order to compel the PSNI to complete their enquiries without any further delay.

“Their abject failure to do so, bearing in mind the considerable work done by the Saville Inquiry, is completely unacceptable, and has significantly undermined the rule of law and administration of justice.”

Joe McKinney’s brother of William was one of the victims.

He said that he was extremely angry that “those responsible for the murders committed on Bloody Sunday are not being pursued with any genuine conviction or rigour by the PSNI.”

In a statement, a PSNI spokesman said: “Police began a scoping exercise earlier this year to determine investigative issues following the publication of the Saville report.

“This has now been concluded and consideration remains ongoing as to the future resourcing of the investigation, which will be both lengthy and complex.

“We are committed to resourcing this investigation into the events of 30 January 1972, but this has to be determined against competing priorities which pose a risk to the public today.”