By Gabriela Baczynska and Steve Gutterman
MOSCOW (Reuters) - Masked Russian police searched the office of a liberal regional governor who has connections with opponents of Vladimir Putin on Tuesday in what Kremlin critics said was part of a campaign to put pressure on foes of the president.
The federal Investigative Committee said law enforcement officers searched the office of Kirov region governor Nikita Belykh as part of a criminal investigation into the alleged theft of 90 million roubles ($3 million).
Belykh denied any wrongdoing and said he was cooperating with the investigation.
A former moderate opposition party leader, Belykh was appointed in 2009 by then-President Dmitry Medvedev in what was seen as an effort to appease liberals pushed to the margins during Putin's 2000-8 presidency and ally them with the Kremlin.
"The searches in Nikita's office are a clear sign of the end of the 'Medvedev thaw'," Maria Gaidar, a critic of Putin and a former deputy to Belykh, said on Twitter. Putin returned to the presidency in May after four years as prime minister.
Opposition leaders accuse the Kremlin of using the court cases and criminal investigations to put pressure on Putin's critics during his new six-year term, but the president's spokesman has denied this.
Boris Nemtsov, an opposition leader who preceded Belykh as head of a liberal pro-business party in the mid-2000s, said the search was aimed not at Belykh directly but at Alexei Navalny, who has helped organize protests against Putin and has been charged in a separate case of theft in the Kirov region.
The Investigative Committee said police, FSB security forces and federal investigators were searching for documents related to the sale of a 25.5 percent state share in a distillery for some 90 million roubles less than its market value, which the committee said was about twice that figure.
"Belykh will be questioned on issues of interest to the investigation," it added in a statement.
Belykh, 37, said on his page on a Russian social networking site that he would be questioned on Wednesday as a witness, and suggested his home had also been searched. He told Ekho Moskvy radio that he had done nothing wrong.
"I am absolutely certain that everything I did was right and correct. Why should I be afraid?" he said.
Footage on state television showed police, some in body armor and black balaclavas, entering the administration building in Kirov, 800 km (500 miles) northeast of Moscow.
"This is a special operation to put pressure on Belykh to give evidence against Navalny," Nemtsov said by telephone.
Navalny has been charged with large-scale theft over the sale of timber while he was working in the Kirov region. He faces up to 10 years in prison if convicted.
Navalny denies any wrongdoing, and Belykh said on a social network site in 2011 that he believed the accusations against Navalny over the timber sale were baseless.
The Investigative Committee spokesman said in December that the authorities were looking into Navalny's possible involvement in the distillery case, according to the Interfax news agency.
Navalny could not be reached for comment. His spokeswoman, Anna Veduta, said Navalny had left the Kirov region before the distillery stake was sold in 2010 and was not involved.
($1 = 30.1805 Russian roubles)
(Editing by Alison Williams/Mark Heinrich)