The Shadow Northern Ireland Secretary Shaun Woodward used his speech to the Labour conference to criticise the British Government for not honouring a promise to hold an inquiry into the death of Pat Finucane.
He said it should honour the commitment by Tony Blair to investigate the shooting of the lawyer by loyalist extremists in Belfast in 1989.
The shooting has generated widespread calls for an inquiry and claims that elements of the security services helped direct the assassins.
The Finucane family are pressing for an investigation which would be as wide and as open as possible.
In July, the lawyer's widow, Geraldine Finucane, said Northern Ireland Secretary Owen Paterson had promised her a decision on the inquiry this year, but had not delivered.