(Adds Russian media report of body flown to Crimea)
KIEV, March 23 (Reuters) - A son of ousted Ukrainian president Viktor Yanukovich has drowned after a mini-van he was driving plunged through ice on a Siberian lake, an aide to Ukrainian Interior Minister Arsen Avakov said.
Authorities in Russia, where Yanukovich has lived with most of his family since protests against his pro-Moscow policies forced him from office in February 2014, did not immediately confirm the death.
Avakov aide Anton Herashchenko said on Facebook that Yanukovich's younger son, also named Viktor, had died on Sunday in Lake Baikal.
The vehicle broke through the ice and tipped over onto the driver's side. Five passengers survived and "four of them didn't even get their feet wet," Herashchenko said.
Viktor, 33, a racing car enthusiast who headed the Ukrainian Automobile Association when his father was in power, was not able to unbuckle his seat belt in time to get out, he added.
Nestor Shufrych, a Ukrainian parliamentary deputy from the Opposition Bloc and a former ally of Yanukovich, gave a similar account on Facebook.
In Moscow, the Kremlin declined comment.
"I do not have any information on the subject," said Dmitry Peskov, the spokesman of Russian President Vladimir Putin. "I can neither deny nor confirm (the report)."
Life News, which has good contacts among Russia's law enforcement authorities, quoted sources as saying the body had been flown by charter flight for burial on the Black Sea peninsula of Crimea, annexed from Ukraine by Russia last year.
The Yanukovich family is known to have owned several properties in Crimea. (Additional reporting by Darya Korsunskaya and Anton Zverev in Moscow,; Writing by Richard Balmforth and Alessandra Prentice; Editing by Gareth Jones)