UK warns of IRA dissident attack

LONDON — Britain raised the terror threat level yesterday posed by Irish Republican Army dissidents, who have mounted repeated attacks in Northern Ireland and recently threatened to target London bankers.

The level has changed from “moderate’’ to “substantial,’’ the middle rung on the five-point threat scale. At such a threshold, an attack is considered a strong possibility.

The existing threat from Al Qaeda-inspired groups in Britain has long been rated at the higher level of “severe.’’

The heightened threat posed by IRA die-hards comes weeks before the annual conference of the governing Conservative Party, long a prized IRA target. In 1984, the outlawed group nearly killed Prime Minister Margaret Thatcher with a bomb that devastated the Conservatives’ conference hotel, killing five.