Moscow Mayor Yury Luzhkov says he will sue several state-linked Russian TV channels after they ran documentaries that were critical of him.
The programmes alleged that Mr Luzhkov used his position to further the business interests of his wife, Russia's richest woman.
They also criticised him for holidaying during a wildfire crisis this summer.
The programmes come amid speculation that Mr Luzkhov has fallen from favour with Russia's president.
Russian media reports have suggested that President Dmitry Medvedev wants Mr Luzhkov - in office since 1992 - removed from his post.
"It is pointless to list all the insinuations that have been voiced," the Moscow government said in a statement on Monday.
It said all the recently broadcast "negative" reports were groundless, and that the mayor and the city of Moscow would "file appropriate defamation suits on each of those accounts".
BBC News
