MOSCOW, March 1 -- Opposition supporters will march through Moscow in memory of Boris Nemtsov, the Kremlin critic whose murder has increased concern about Russia's future among opponents of President Vladimir Putin.
Thousands of people laid flowers and lit candles on Saturday on a bridge near the Kremlin where the opposition politician and former deputy prime minister was shot to death late on Friday.
The opposition said Moscow city authorities had approved Sunday's march from 3pm local time (12:00 GMT), allowing for up to 50,000 people, though the organisers say more could show up to march alongside the River Moskva.
National investigators who answer to Putin say they are pursuing several lines of inquiry, including the possibility that Nemtsov, who was 55, was killed by Muslim attackers or that the opposition killed him to blacken the president's name. Putin's opponents say such suggestions show the cynicism of Russia's leaders as they whip up nationalism, hatred and anti-Western hysteria to rally support for his policies on Ukraine and deflect blame for an economic crisis.
"It is a blow to Russia. If political views are punished this way, then this country simply has no future," Sergei Mitrokhin, an opposition leader, said of Nemtsov's murder. Putin has described the killing as a "provocation", and told Nemtsov's 86-year-old mother, Dina Eidman, that the killers would be found and punished. He also promised to do everything possible to bring to justice those responsible for Nemtsov's killing.
"Everything will be done so that the organisers and perpetrators of a vile and cynical murder get the punishment they deserve," Putin said in a telegram to Nemtsov's mother published on the Kremlin's website. He said Nemtsov's death was an irreparable loss and that he had "left his trace in Russia's history, in politics and public life".
Nemtsov was one of the leading lights of an opposition struggling to revive its fortunes three years after mass rallies against Putin failed to prevent him from returning to the presidency after four years as prime minister.
Putin has now been Russia's dominant leader since 2000, when ailing President Boris Yeltsin chose the former KGB spy as his successor, a role Nemtsov had once been destined to play.