ANTRIM, United Kingdom - Northern Ireland's fragile power-sharing government was locked in a war of words on Sunday as republican leader Gerry Adams spent a fourth day being questioned over an infamous IRA murder.
First Minister Peter Robinson attacked Adams's Sinn Fein party for "despicable" remarks indicating that it would review its involvement with policing in the province after the arrest, which Sinn Fein says is politically motivated.
Sinn Fein's support for the police was a key part of the 1998 Good Friday agreement that ended decades of Protestant-Catholic violence in Northern Ireland and led to the creation of a power-sharing government in Belfast.
But tensions have risen since Wednesday's arrest of Adams, a key figure in the peace process, over the murder of mother-of-10 Jean McConville by the Irish Republican Army in 1972.
Police must charge 65-year-old Adams, release him or apply to extend his detention by Sunday night.
A source close to Adams, who has strongly denied any involvement in the murder or membership of the IRA, told the BBC that the political leader was being questioned "for 17 hours a day".
"The publicly conveyed threat to the PSNI (Police Service of Northern Ireland) delivered by the highest levels of Sinn Fein that they will reassess their attitude to policing if Gerry Adams is charged is a despicable, thuggish attempt to blackmail the PSNI," said Robinson.
Robinson's Protestant conservative Democratic Unionist Party, which wants Northern Ireland to stay in the United Kingdom, shares power with Catholic republican Sinn Fein, which was the political wing of the now-defunct IRA and wants Northern Ireland to join the Republic of Ireland.
Northern Ireland's devolved government was suspended on several occasions between 1998 and 2007 due to political disagreements, but has operated uninterrupted since 2007.
During a rally on Saturday by hundreds of Sinn Fein supporters at the unveiling of a new painted mural of Adams, Deputy First Minister Martin McGuinness said the arrest was "political policing."
McGuinness, a former IRA commander, said there were still "dark forces" in the police who were opposed to the peace process, and added that the party would review its relationship with police in Northern Ireland.
McConville's children watched as she was dragged screaming from their Belfast home in 1972 after the IRA accused her of being an informer. Her remains were found buried on a beach in 2003 and tests found she had been shot in the back of the head.
Around 3,500 people died in three decades of violence in Northern Ireland known as "The Troubles."
The province has been largely peaceful but sporadic attacks continue, blamed on dissident republicans opposed to the peace process, and communal unrest erupts from time to time.