The owner of Russia's Kommersant Publishing has fired an editor and a senior manager over what he described as a breach of ethics for its coverage of alleged voting fraud during parliamentary elections earlier this month.

Alisher Usmanov criticized the Kommersant Vlast weekly magazine, saying its coverage of Prime Minister Vladimir Putin's United Russia party in recent issues bordered on “petty hooliganism.” Usmanov fired the magazine's editor, Maxim Kovalsky, and the holding company's general director, Andrei Galiyev.

The firings were confirmed Tuesday by the general director of the Kommersant publishing house, Demyan Kudryavtsev, who also offered his resignation.

On Saturday, tens of thousands of Russians took part in anti-government protests against the December 4 parliamentary elections, alleging they were rigged to favor United Russia. The demonstrators called for the official results to be annulled and for a new election.

Usmanov is a billionaire and one of Russia's richest men. He is also a major shareholder in London's Arsenal Football Club.

United Russia — which has dominated Russian politics for more than a decade — took about 50 percent of the vote and now holds a slim majority in the State Duma, or the lower house. But opposition parties and observers contend the winning results were probably inflated. The ruling party's leaders have denied cheating.

The Communists, along with the nationalist Liberal Democrats and Just Russia — a social democratic party — all made strong gains in the vote, meaning United Russia will be forced to work with the newly empowered opposition.

If he regains the presidency, the 59-year-old Mr. Putin could serve two more six-year terms and remain in power until 2024. He was first elected president in 2000.

On Monday, Russian tycoon Mikhail Prokhorov, one of Russia's richest men and the principal owner of the National Basketball Association's New Jersey Nets, announced he will challenge Prime Minister Putin's bid for the presidency.

The parliamentary win puts Mr. Putin on course to win the March election, which would return him to the president's office. He was president from 2000 to 2008 and retained great power as the country's prime minister.