Georgian Finance Minister Nodar Khaduri said on November 28 that the investigation is not new.
He says it began two years ago but was later suspended.
According to Khaduri, the audit is related to taxes and has nothing to do with politics.
The Tbilisi mayor's office announced on November 27 that its seven departments are currently under investigation by the prosecutor-general, the Finance Ministry, and the Interior Ministry.
Mayor Gegi Ugulava is a close associate of President Mikheil Saakashvili.
A number of investigations were launched against officials representing Saakashvili's United National Movement party after current Prime Minister Bidzina Ivanishvili's Georgian Dream coalition won parliamentary elections in October.