Gerry Adams has been warned of a “credible” death threat, Sinn Fein said.
The party blamed those opposed to the peace process for the message, which it said was passed by police to Mr Adams’ wife while he was not at home.
Mr Adams, 65, has been released from Antrim Police Station, pending a report being sent to prosecutors, after four days of questioning about the notorious 1972 killing of mother-of-10 Jean McConville, and other alleged links with the IRA.
Sinn Fein Stormont Assembly member Raymond McCartney said: “The PSNI (Police Service of Northern Ireland) officer told Gerry Adams’ wife Collette that they had information of a credible threat to the life of Gerry. Clearly there are elements that are opposed to the peace process and anti-Sinn Fein.”
Mr Adams has vehemently rejected allegations made by former republican colleagues that he ordered the abduction and killing of Mrs McConville.
The decision whether to charge him will be made by the Public Prosecution Service after reviewing evidence presented by police.
A son of Mrs McConville meanwhile has said Mr Adams threatened him with a “backlash” if he released the names of those he believed were responsible. Michael McConville has said his family’s fight for justice will go on after the Sinn Fein leader was freed, but has maintained he could be shot if he disclosed the identities of suspects to police.
Mr McConville said Mr Adams “could” have meant a backlash against the peace process but he took it to mean a “backlash from republican people”.
Mr Adams meanwhile yesterday refocused on campaigning with the republican party holding European election rallies in Belfast and Dublin tomorrow, as the Sinn Fein president resumes the canvassing he claims his detention was designed to thwart.
The former MP for west Belfast and now representative for Co Louth in the Irish parliament criticised the police’s handling of his arrest but moved to dispel any suggestion that Sinn Fein’s commitment to policing had wavered in the wake of the affair.
His arrest on Wednesday triggered a bitter political row at Stormont, with Sinn Fein accusing an “anti-peace process rump” within the PSNI of orchestrating the detention to damage the party ahead.