(Adds new death toll, details)
KIEV, May 2 (Reuters) - At least three people were killed and several wounded when pro-Russian activists attacked supporters of Ukrainian unity marching through Odessa, deepening rifts in the largely Russian-speaking port city.
The opposing sides have clashed before in the Black Sea port, but the battles have never resulted in deaths and some residents said they feared both may now try to seek retribution.
The regional police said three were killed, at least one by a gunshot to the chest, when a march by the pro-Kiev demonstrators was ambushed. Petrol bombs, paving stones and explosive devices were thrown during the clashes, they said.
Dmytro Spivak, a local parliamentarian, told Ukrainian television that four young supporters of the authorities in Kiev had been killed.
"It is abundantly clear that the pro-Russian side was very well armed, well organised and that this action was planned long ago," he said, adding the police did little stop the clashes. "I will say one thing to (Russian President Vladimir) Putin; forget about Odessa."
Ukraine's new pro-Western leaders have accused Moscow of supporting pro-Russian groups to try to destabilise a country desperately trying to recover from months of upheaval that ended in the toppling of President Viktor Yanukovich in February.
The Kremlin denies playing any role in the uprisings in the east and south of Ukraine, saying Russian-speakers there are simply protecting their rights against possible assault by Kiev's pro-Western leaders. (reporting by Natalia Zinets and Elizabeth Piper, writing by Elizabeth Piper, editing by Mark Heinrich)