Irish police have been asked to interview self-confessed IRA bomber Michael Hayes by lawyers acting for the Birmingham pub bombings inquests.
Mr Hayes, 69, recently told a BBC interview that he accepted "collective responsibility" for the 1974 double bombing but did not know who planted the devices which killed 21 people.
A pre-inquest review in Birmingham on Thursday was told by lawyers for coroner Peter Thornton QC that "a request to the Irish gardai to interview Mr Hayes" had been made.
Peter Skelton QC, counsel to the inquests, added: "We're discussing our involvement in any interview with West Midlands Police."
The force also confirmed in the hearing that it was "also considering an application for My Hayes to be interviewed".
Footage of the interview has already been requested.
The news came as the campaign group Justice4the21, whose work brought about the fresh inquests, announced it was boycotting the hearings.
In a statement, campaigners said they will "no longer participate" after Mr Thornton ruled out naming alleged suspects in evidence at the inquest.
Lawyers for 10 families, in a joint statement, said they would try to crowd-fund a judicial review of the coroner's ruling on what is known as the perpetrator issue.
The legal team representing the family of brothers Eugene and Desmond Reilly were present for the latest inquest review hearing.
Also present was the youngest victim Jane Davis's brother Brian Davis, from Ilkley, near Leeds.
He spoke of his "dismay" the other families had decided not to attend but understood why.
Mr Davis, who left Birmingham in the 1980s, "absolutely" welcomed the decision to ask Irish police to interview Mr Hayes.
He told the coroner: "It seems bizarre to me that journalists and serving MPs can track down these people and name them publicly, on TV, but the police and judiciary fail to be able to do the same thing."
Heather Williams, barrister for the Reilly brothers' loved ones, said her instructing solicitors had not had any advance notice of the other families' decision not to attend.
Speaking at the hearing, which began an hour later than planned after news of the relatives' boycott was digested, Mr Thornton said "the door will always be open".
He added: "Clearly the inquest into the deaths of the 21 who died on November 21 1974 will proceed in any event.
"I have a public duty to conduct them and was appointed by the Lord Chief Justice to do so."
Concluding the hearing, Mr Thornton said it was "unlikely the inquests will commence until certainly December, maybe later - maybe substantially later - I just cannot say at the moment".
He said the inquests would have to await the outcome of the judicial review application process.
In the statement, Justice4the21 said its boycott was based on the fact that material held by Devon and Cornwall Police, who reviewed the original criminal investigation, had not been disclosed to the families.
The relatives also made reference to the Hayes interview, saying "it remains unclear how the information provided by PIRA (Provisional IRA) bomb-maker Mick Hayes, will be investigated and by who".
After the hearing, Brian Hambleton, whose sister Maxine died in the bombings, said the police needed to speak to Hayes.
He said: "We have West Midlands Police telling people the case is still open.
"They've had an opportunity - they've got a man (Hayes) speaking out over two weeks ago now and no-one appears to be doing anything it.
"If the case is still open, you've got someone there who needs to be spoken to."
Bill Craig, whose brother James died in the bombings, said: "We want the inquest jury to hear the full scope - what happened from the moment James McDade blew himself up in Coventry.
"Otherwise how can they make a decision?
"We're not asking for a criminal trial or to find anybody guilty but, like the Hillsborough hearings, if any action does need to be taken, then the Crown Prosecution Service can do that.
"That is all we are asking."
The next pre-inquest review will be held on September 14.