Opposition leader Alexei Navalny, pictured in May, was recently arrested for election fraud. His group claims the Russian government fabricated evidence of fraud in order to eliminate competition ahead of local elections in September. Agence France-Presse/Getty Images

An investigation began Wednesday into a case in which members of a Russian opposition party were disqualified from running in local elections and subsequently jailed. The Russian government charged the politicians, many of whom were outspoken critics of Russian President Vladimir Putin, with election fraud. The coalition said the allegations were falsified and served to eliminate competition ahead of elections in the northern city of Novosibirsk this fall.

"We are talking here about fulfilling certain actions defined by the law," said Dmitry Peskov, a Kremlin spokesman, as reported by the state-sponsored news agency Ria Novosti, via Agence France-Presse. The investigating committee claimed that some of the signatures collected by the candidates to register for the elections were falsified.

Leaders of the coalition, including well-known Kremlin critic, writer and political hopeful Alexei Navalny, were arrested Monday. They have been on a hunger strike since their arrest and said they will not stop until they are allowed to run in the September elections.

Boris Nemtsov, an opposition leader and former first deputy prime minister, gestures during a protest against Russian President Vladimir Putin in central Moscow in 2012. Nemstov was assassinated in February, and the case has never been solved. Members of his party contend that Putin was responsible. Agence France-Presse/Getty Images

The People's Freedom Party-Parnas coalition, the opposition group at the center of the controversy, recently joined with Navalny's Progress Party in April 2015, creating a powerful alliance. The formerly separate political groups were united over common goals and a common enemy: Putin.

Former deputy Prime Minister Boris Nemstov founded the People's Freedom Party and led the group until his assassination in February. Nemstov was shot to death outside the Kremlin, and though Russian authorities arrested Chechen rebels almost immediately afterward, many Nemstov supporters insisted he was murdered by members of Putin's government.

Novosibirsk is the third-largest city in Russia after Moscow and St. Petersburg, with more than 1.5 million residents, and the elections were thought of as a dry run for parliamentary elections later in the year.

The elections in Novosibirsk are slated for Sept. 13.