MOSCOW (AP) — About 400 demonstrators gathered in central Moscow to protest alleged tampering in the national parliament election in which the dominant pro-Kremlin party retained a constitutional majority.

The Saturday demonstration at Pushkin Square was organized by the Communist Party, which increased its share of seats in the State Duma in the election but is contesting the results from online balloting that accounted for some 2 million votes in Moscow.

No arrests were made at the protest, but the Communists said about 60 of their activists had been detained ahead of the demonstration. Many were released after being held for a few hours.

Official results gave the United Russia party, which is loyal to President Vladimir Putin, 324 seats in the 450-member Duma, more than the two-thirds majority needed to change the constitution. The Communists are the second-largest faction with 57 seats, up from their previous 42; three other parties also won seats.