World

Since its formation in 1970, the 6,400-member Ulster Defense Regiment, the British army's largest, has lost 180 men, nearly all to terrorists of the outlawed Irish Republican Army. Terrorist acts are also committed regularly by extremists on the Protestant side, most of them members of paramilitary groups like the illegal Ulster Freedom Fighters. Last week, acting on growing evidence that members of the U.D.R. were leaking confidential information on I.R.A. suspects to such Protestant extremist groups, Belfast police took the ; unprecedented step of mounting raids against a fellow security force. Some 300 members of the Royal Ulster Constabulary detained 28 U.D.R. soldiers. Twenty- two of them were released, and six were charged with possession of ammunition and a firearm.

The arrests were prompted in part by the murder last August of Roman Catholic Loughlin Maginn, 29. The appearance of his name on a leaked list obtained by the Ulster Freedom Fighters is believed to have led to his death. Last month two U.D.R. men were charged with Maginn's murder.