Moscow Mayor Sergei Sobyanin has announced he will seek another term in the Russian capital's election set for September 9.

Sobyanin, who has been Moscow's mayor since 2010, made the announcement in a statement posted on his website on May 27.

In his statement, Sobyanin said the work of his administration "has not been fully completed…although the most difficult and painful part is already behind us."

Liberal opposition politician Ilya Yashin announced on April 11 that he will participate in the election.

Yashin's candidacy was endorsed by opposition leader and anticorruption activist Aleksei Navalny, who came in second in the 2013 Moscow mayoral election with more than 27 percent of the vote.

Sobyanin, 59, formerly served as governor of Tyumen Oblast, deputy prime minister, and head of presidential administration. Then-President Dmitry Medvedev appointed him Moscow mayor in 2010, replacing longtime Mayor Yury Luzhkov.