The IRA has offered to shoot its members blamed for the murder of Robert McCartney.

The announcement, which was strongly criticised by politicians in Britain and Northern Ireland, failed to sway McCartney's family, who want the killers brought to justice.

Eddie McGrady, an MP for the moderate nationalist SDLP, said: "This appalling proposal is an extremely dangerous slide into anarchy and is a threat to the entire community of Northern Ireland."

Paul Murphy, the Northern Ireland secretary, added that he was appalled by the statement.

"Any sort of punishment ought to come through the courts, through due process of the law," he said.