MOSCOW, May 1 (RIA Novosti) - Around 30,000...

"The situation is calm, everything is proceeding according to plan. Everyone is in a festive mood," Viktor Biryukov said.

May 1 is Spring and Labor Day across Russia, a national holiday. In Soviet times May 1 saw massive pro-Communist Party rallies.

Russia's modern political parties have also taken the opportunity to hold rallies, with supporters of the ruling United Russia party, the Communist Party, the ultranationalist LDPR party and A Just Russia taking part in rallies across the city. An opposition 'March of Dissent' is taking place in St. Petersburg with the participation of several hundred demonstrators.

Biryukov said the biggest rally had taken place on Tverskaya Square and involved about 23,000 people, adding that about 9,000 police, Interior Ministry troops and special police units were ensuring law and order.

"Metal detectors have been installed at the sites of the biggest events," he added.