FILE PHOTO: Russian opposition leader Alexei Navalny smiles in the studio of the radio station Echo of Moscow in Moscow, Russia December 27, 2017. REUTERS/Sergei Karpukhin

MOSCOW (Reuters) - Russian police searched the campaign headquarters of opposition leader Alexei Navalny in St Petersburg on Thursday ahead of a presidential election on March 18, a video feed streamed live to the Internet by Navalny’s supporters showed.

The feed showed police checking campaigners’ passports. Russia’s central election commission declined to register Navalny as a candidate in the election, citing what Navalny said was a trumped up criminal conviction.

Thursday’s police search took place on the same day as President Vladimir Putin, who polls show is on track to be comfortably re-elected, was visiting St Petersburg.