Russian police officers gather at the entrance to a business centre, which houses the office of opposition leader Alexei Navalny's Anti-corruption Foundation (FBK), in Moscow on January 28, 2018. (AFP PHOTO)

MOSCOW, Jan. 28 (Xinhua) -- Russian law enforcement officers raided the Moscow office of opposition leader Alexei Navalny's Anti-Corruption Foundation on Sunday, detaining a number of staff members, said the foundation's spokesperson.

The police forced their way into the office on account of a phone call reporting bomb threat and evacuated the building, the foundation's spokeswoman Kira Yarmysh said on Navalny's YouTube channel.

Several employees of the foundation were detained, according to Yarmysh.

Navalny's supporters have concluded a rally of more than 100 people in Barnaul of Russia's Altai Republic, the regional branch of the Interior Ministry said Sunday.

Russia's RIA Novosti news agency reported earlier that Navalny's supporters had submitted an application to the Moscow municipal government on holding protests on Sunday involving 15,000 people at the downtown of Moscow, which was later rejected.

Navalny has been calling on voters to boycott the presidential race scheduled for March 18, which he claimed to be a rigged "pseudo-election."

Earlier this month, Russia's Supreme Court rejected an appeal by Navalny and upheld a ban on his participation in the 2018 presidential election for his conviction of embezzlement at a timber company.