ITV News reporter Marc Mallett says it is understood that Gerry Adams met with his solicitor today after returning from a visit to the Irish parliament in Dublin, with both going to the police station for his questioning.
He adds that while Mr Adams volunteered to be interviewed over Jean McConville's abduction and murder, the subsequent arrest would be "standard procedure" for detectives conducting the investigation.
Mr Adams denies any involvement in Mrs McConville's abduction, killing or subsequent burial.
Adams attacks reasons for his detention and denies McConville murder
It is claimed IRA volunteers described what happened the night Jean McConville was murdered to Boston College's "Belfast Project".