Gerry Adams yesterday said he made himself available to talk to police after a “sustained, malicious, untruthful and sinister campaign” against him alleging his involvement in a notorious IRA murder.

Speaking at a press conference following his release from custody after four days of questioning about the killing of Belfast mother-of-10 Jean McConville, the Sinn Fein president said he was “concerned about the timing” when the Police Service of Northern Ireland (PSNI) contacted his solicitor on Monday afternoon.

But Adams said: “I want to make it clear that I support the PSNI.”

Downing Street confirmed that David Cameron and Taoiseach Enda Kenny had spoken earlier in the day to discuss the situation surrounding Adams’s arrest, but would not give any further details.

I have worked hard with others to have this injustice redressed

Adams exited Antrim Police station through a rear exit while loyalist protesters waved Union flags and staged a sit-down protest in front of the heavily fortified station.

A file will be sent to prosecutors by detectives who have questioned him over the murder.

The move means the ultimate decision whether to charge the 65-year-old politician with any offence will be made by Northern Ireland’s Public Prosecution Service (PPS) at a later date.

He has always vehemently denied allegations he ordered the 37-year-old widow’s death in 1972.

Adams thanked everyone for the support he had been shown, adding: “Let me very clear – I am innocent of any involvement in any conspiracy to abduct, kill or bury Ms McConville.

“I have worked hard with others to have this injustice redressed and for the return of the bodies of others killed during the conflict and secretly buried by the IRA, and I will continue to do so.”