Lawyers for seven former paratroopers facing questioning over the 1972 Bloody Sunday killings have begun legal action against the police, at the high court in London.

Papers seeking a judicial review of the way in which Police Service of Northern Ireland detectives are conducting their historical inquiry were lodged with the administrative court on Wednesday.

In their application, handled by a City firm of solicitors, the ex-paratroopers’ identities are protected under the anonymous letters of the alphabet given to the soldiers during the Saville inquiry into the shootings in Derry, which left 14 civil rights protesters dead.

The PSNI on Wednesday evening released a former member of the Parachute Regiment, identified only as Lance Cpl J, after interviewing him in Belfast for several days.

The other ex-paratroopers are understood to be seeking advance notice from the PSNI of any request for police interviews over the shootings and want questioning to take place at local police stations near their homes in England.

Asked about the legal action launched by the soldiers, a PSNI spokesman said: “It would be inappropriate to comment.”

An MoD spokesperson said: “We are aware that an application for judicial review has been submitted by a number of former soldiers against the Police Service of Northern Ireland in connection with their ongoing investigation into the events of Bloody Sunday.

“That action has been taken by the soldiers concerned on the advice of their independent legal representatives. The Ministry of Defence is not a party to these proceedings.”

If former Parachute Regiment soldiers are convicted of murder on Bloody Sunday, their sentencing will create a political dilemma. Under the terms of the Good Friday agreement, the reduced, maximum term of two years for scheduled offences was backdated only to the beginning of direct rule from Westminster.

Bloody Sunday took place in January 1972, before the Stormont executive was replaced. Lawyers for any paratrooper convicted could nonetheless apply for a royal pardon for their client or for the early release scheme to be applied in their case.

The threatened arrests of more ex-paratroopers has provoked anger among many former soldiers who have complained about what they say is persecution of security personnel.

The Facebook account of the Parachute Regimental Association carries a message from the colonel commandant of the regiment, Lieut Gen John Lorimer. It says: “While the regiment cannot comment on an ongoing PSNI investigation it is important that the wider regiment knows that RHQ [regimental headquarters] is in communication with the appropriate department within the MoD and army HQ; and that the former member of the regiment [who was arrested] is being offered the appropriate support.

“The colonel commandant appreciates that this is a difficult time for both the veteran and his family, and assures them of our support while this case is being investigated. He would also like to remind all our former servicemen that RHQ is able to offer support should it be required.”

Daniel Holder, of the Belfast-based human rights organisation the Committee on the Administration of Justice, said: “Whilst it is argued there is too much focus on the activities of the state the reality is that legacy investigations have not led to one single conviction of a solider or police officer since the 1998 Good Friday agreement. This is despite the emergence of abundant evidence of state wrongdoing. To date there has been virtual impunity.

“In relation to unresolved Troubles murders, HM Inspector of Constabulary looked at the numerous referrals for further investigation made by the now stood-down police historical inquiries team. It found that not one of the cases taken forward was a state involvement case, and that the unit had given such preferential treatment to state cases that it had acted unlawfully.

“Where human rights violations are concerned, accountability is vital for non-recurrence. Last December, the UK government agreed to set up a new system to investigate the past under the Stormont House agreement, yet in recent months has sought to introduce unworkable ministerial ‘national security’ vetoes into the implementation legislation. We need the past to be dealt with in good faith and will be keeping an eye on developments going forward.”

Earlier this week, Northern Ireland’s Public Prosecution Service confirmed that another retired soldier, Dennis Hutchings, 74, who lives in Cornwall, is to be prosecuted for attempted murder.

John Patrick Cuningham, who had learning difficulties, was shot dead in 1974 by an army patrol in Benburb, a village on the border betwen Counties Armagh and Tyrone. Hutchings is the first ex-soldier to be charged with Troubles-related offences since the signing of the Good Friday agreement in 1998.