Sinn Fein leader Gerry Adams says his arrest over the murder of Jean McConville is wrong but insists the police in Northern Ireland retain his support.

After four days in custody Adams again rejected allegations made by former republican colleagues that he ordered the abduction and killing of the Belfast mother-of-ten in 1972.

Adams’ arrest on Wednesday triggered a bitter political row at Stormont, with Sinn Fein accusing an “anti-peace process rump” within the police of orchestrating the detention with the aim of damaging the party.

This was angrily rejected by unionists, whose fury intensified when senior Sinn Fein figures indicated that their support for the Police Service of Northern Ireland (PSNI) – a critical plank in the peace process – would be “reviewed” if Adams was charged.

Adams on Sunday night moved to reaffirm his party’s commitment to new policing structures in the region.

While he said his arrest had sent out the “wrong signal”.

“Despite this I want to make it clear that I support the PSNI, I will continue to work with others to build a genuinely civic policing service.

“The old guard which is against change – whether in the PSNI leadership, within elements of unionism, or the far fringes of self proclaimed but pseudo republicans – they can’t win.

“The dark side of the British system cannot be allowed to deny anyone, any of our people – Catholic, Protestant or dissenter – to their entitlement to a rights-based citizen society as set out in the Good Friday Agreement.”

A rapturous welcome afforded to the republican veteran – as he gave his first public reaction to his detention – in a Belfast hotel – was in stark contrast to the angry loyalist protest staged outside Antrim police station when news of his release filtered through.

Adams, 65, urged people to acknowledge the feelings of the McConville family with the intense focus on the 37-year-old widow’s death.

But he said claims that he was involved were part of a “sustained, malicious, untruthful and sinister campaign”.

The decision to release Adams and send a report to the Public Prosecution Service (PPS) means the ultimate decision whether to charge him with any offence will be made by prosecutors at a later date after reviewing evidence presented by police.