Senator Edward Kennedy has called on the IRA to disband and has accused republicans of covering up Robert McCartney's murder.

Kennedy, who is Sinn Fein's most powerful American ally, met with the sisters and partner of McCartney in Washington yesterday.

The senator has already cancelled his traditional St Patrick's day meeting with the Sinn Fein leader, Gerry Adams.

After meeting the sisters he said: "Their presence in Washington on this St Patrick's Day sends a very powerful signal that it's time for the IRA to fully decommission, end all criminal activity, and cease to exist as a paramilitary organisation."

"There's no question Sinn Fein and the IRA are involved in a cover-up there. Gerry Adams has to free himself.

Michael Howard yesterday raised the issue of government support for Sinn Fein in the Commons, following complaints from the SDLP that private deals had excluded other parties.