By Maria Tsvetkova
MOSCOW (Reuters) - Russian opposition leader Mikhail Kasyanov said on Wednesday he was attacked by Cossacks and pro-Kremlin activists as he prepared to address supporters in southern Russia and had filed a criminal complaint with the police.
Kasyanov, a former prime minister, is trying to whip up support for his People's Freedom Party or PARNAS, ahead of parliamentary elections next month. His colleague, prominent opposition leader Boris Nemtsov, was shot dead last year.
Kasyanov, 58, told Reuters in an interview in February he feared for his life after that killing but would not flee Russia.
On Wednesday, he said he was attacked by about 40 pro-Kremlin activists close to a campaign event in Stavropol, about 1200 kilometers (745.65 miles) south of Moscow.
"Thirty to forty people attacked us and tried to cause us physical harm," Kasyanov said in a statement, saying his bodyguards had to act to protect him.
Pavel Lebedev, a local PARNAS activist who said he witnessed the attack, told Reuters the incident occurred when a group of aggressive men, including Cossacks, surrounded Kasyanov outside a conference hall and tried to prevent him entering.
"They pushed him, there were punches, they grabbed his hands, threw tomatoes," said Lebedev.
A police source told the Interfax news agency the authorities were aware of the attack.
A video posted online showed a man holding a giant plane ticket with Kasyanov's name on it trying to stop the politician entering the hall while shouting that the ticket was for Washington.
Kremlin supporters and state TV channels often accuse Russia's liberal opposition of working for the United States. The liberal opposition, which is starved of air time on state TV, denies that. It is likely to struggle to win any of the 450 seats in Russia's lower house of parliament.
(Editing by Andrew Osborn)