Northern Ireland police have arrested Sinn Fein leader Gerry Adams during an investigation into one of the country's most notorious murders.

The Sinn Fein Party, the second largest opposition party in Northern Ireland, said on Wednesday that Adams was being questioned by police investigating the 1972 abduction and murder of Jean McConville, a mother of ten children. The Police Service of Northern Ireland [PSNI] said a 65-year-old had been arrested by detectives investigating the killing.

In the 1980s, Adams was spokesman for the Irish Republican Army (IRA), which fought against British rule. He reinvented himself as a Northern Ireland peacemaker and then as a populist opposition politician in parliament.

Adams rejects involvement in McConville's killing.

"I believe that the killing of Jean McConville and the secret burial of her body was wrong and a grievous injustice to her and her family," he said in a statement.

"Well publicised, malicious allegations have been made against me. I reject these," he added.

Alleged informer

McConville had been suspected by the IRA as being an informer, a charge her family has always denied.

The investigation into her killing has been revived by the release of a series of interviews given by former fighters from the Northern Ireland conflict to Boston College.

As head of the political wing of the IRA, Sinn Fein, Adams was a pariah during the 1980s in the UK and was banned from speaking on British television.

He later helped broker a 1998 peace deal that largely ended three decades of violence between Catholic fighters seeking union with Ireland and mainly Protestant opponents, who wanted to maintain Northern Ireland's position as part of the UK. 

Popular figure

Since the peace deal, Adam's role as a statesman has grown. He has visited the White House and was a guest of honour at the funeral of Nelson Mandela, the former South African president, last year.

It is unclear what affect the arrest might have on Northern Ireland's power-sharing government, whose deputy first minister, former IRA commander Martin McGuinness, is also a member of Sinn Fein who has reinvented himself as a statesman and met the Queen in 2012.

The arrest is likely to have major ramifications in the Republic of Ireland, where Adams' Sinn Fein party campaigns against the government's austerity policies.

Source: Al Jazeera and agencies