(Corrects gender of photographer in fourth paragraph)
KIEV, May 9 (Reuters) - Ukrainian forces attacked police headquarters in the south-eastern port city of Mariupol on Friday in an attempt to drive out pro-Russian militants, and the building caught fire, according to a Ukrainian parliamentary deputy.
The deputy, Oleh Lyashko, said eight rebels had been killed in fighting. But Donetsk medical authorities said three had been killed, and 25 wounded.
Mariupol, situated in the "People's Republic" declared by local pro-Russian rebels, has been the focus of days of skirmishing between Ukrainian police and separatist gunmen. The area is due to hold a referendum on secession on Sunday that Kiev has declared illegal
A local photographer at the scene told Reuters the police headquarters, a three-storey stone building, was ablaze and that he had seen two bodies lying in the street outside.
"One of them is definitely a police officer," he said.
Local police in the eastern Donetsk region said they could not comment.
Lyashko said a Ukrainian police commander had been killed by a sniper and one had been wounded.
Tetyana Ignatchenko, a journalist in Mariupol, said there was fierce fighting outside the police headquarters.
Ukrainian forces had brought several armoured cars into the town, a major industrial and shipping centre with a population of about half a million, she said.
Local media said separatists had seized a tank in the centre of town and built barricades around the town. There was no confirmation of that report. (Writing by Ralph Boulton; Editing by Aleksandar Vasovic)