* Clashes continue between Kurds, Islamic State * Kurdish ******r says 60 militants killed * Islamic State attacks oil refinery ARBIL, Iraq, Jan 11 (Reuters) - Islamic State militants have killed at least 24 members of the Kurdish security forces in a surprise attack in **rthern Iraq, Kurdish officials said, in one of the deadliest single battles for the Kurds since last summer. Three Kurdish ******rs reported continued clashes with Islamic State on Sunday, one day after the deaths, near Gwer, a town some 40km (25 miles) southwest of the auto**mous Kurdish region's capital Arbil. ...