Moscow's ex-mayor Yury Luzhkov signed a quarter of his decrees in secrecy, including those dealing with construction tenders, Finance Minster Alexei Kudrin said on Tuesday.
The decrees were not published, which is against the law, Kudrin said.
They dealt with the capital's construction tenders, won in most cases by Luzhkov's billionaire property developer wife, Yelena Baturina, and social benefits.
Luzhkov and Baturina are facing possible criminal prosecution as investigators have launched a probe into a property deal involving Baturina's construction company Inteko.
State TV accused Luzhkov of using his position to make his wife the third richest woman in the world on the Forbes list, with an estimated $2.9 billion fortune.
Luzhkov was sacked by President Dmitry Medvedev last week over "loss of confidence" after weeks of sniping in the media between the Kremlin and Moscow City Hall.
MOSCOW, October 5 (RIA Novosti)
