Russian opposition leader Boris Nemtsov, a fierce critic of President Vladimir Putin, has been shot dead in central Moscow ahead of a major opposition rally this weekend, investigators and police said.
An interior ministry spokesman said "a man with documents in the name of Boris Yefimovich Nemtsov was killed," declining to give further details.
Russia's Investigative Committee confirmed the death, saying it had opened a criminal probe.
"According to preliminary information, an unidentified person shot at Boris Nemtsov no fewer than 7-8 times from a car as he was walking along the Bolshoi Moskvoretsky bridge," investigators said in a statement.
The committee, which reports directly to Mr Putin, said that "experienced" investigators had been put on the case.
Mr Nemtsov launched his political career as the governor of Nizhny Novgorod region in central Russia and became a vice prime minister in the late 1990s under the presidency of Boris Yeltsin.
After leaving parliament in 2003, he helped establish and led several opposition parties and groups.
Mr Putin has condemned the killing, saying it looks like a contract killing.
He added that it could be a "provocation" ahead of this weekend's rally.
Mr Putin's spokesman Dmitry Peskov said the president had been quickly informed of the killing and ordered the security agencies to investigate.
