German Chancellor Angela Merkel is "shocked by the devious murder" of the prominent Russian opposition politician Boris Nemtsov, her spokesman said Saturday.

Merkel called on Russian President Vladimir Putin "to ensure that the murder is investigated and the perpetrators brought to justice," spokesman Steffen Seibert said.

"She salutes the courage of the former deputy prime minister, who has repeatedly voiced criticism of the government‘s policies," Seibert said.

Nemtsov, 55, was shot from a passing car while he was walking on a bridge near the Kremlin, Russian police said late Friday.

Nemtsov served as a deputy prime minister under Boris Yeltsin and had been a constant critic of Putin since he came to power in 2000. Since 2013, Nemtsov was a member of the parliament representing the Yaroslavl region north of Moscow.