Asked about claims Gerry Adams's arrest was politically motivated, David Cameron's official spokesman told a regular Westminster media briefing: "This is entirely - and rightly so - an independent police matter.
"The fact that there has been an ongoing investigation into this for a period of time is a well-known matter of public record."
The spokesman declined to say whether Downing Street had been given advance notice of the arrest by police.
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".