MOSCOW: Russian police have seized thousands of copies of a critical book on the country`s powerful Prime Minister Vladimir Putin penned by an opposition leader, his party said Wednesday.

Liberal opposition leader Boris Nemtsov`s book entitled "Putin: the Toll, 10 years," was described by police as "extremist literature," Solidarity party spokeswoman Olga Shorina told the Interfax news agency.

"We sent the books by train and as they were being loaded onto a car, they were confiscated" by police in the northern city of Murmansk, she said.

Shorina also said two people unloading the books from the train were interrogated.

Nemtsov, who was deputy prime minister in Boris Yeltsin`s government in 1997-1998 and one of the group of young reformers at Russia`s helm in the 1990s, had joined the opposition and became a vocal opponent of Yeltsin`s successor Putin.

Russia is heading for presidential elections in 2012 and speculation has been buzzing that Putin may be planning a return to the Kremlin after handing over the presidency to his protege Dmitry Medvedev in a carefully choreographed election in 2008.

BDST: 1033 HRS, August 26, 2010