Former labor minister Toshio Yamaguchi, 66, who has been sentenced to 3 1/2 years for his role in a 1990s loan scam, was taken by prosecutors to prison Thursday, sources said.

Yamaguchi, who has already spent a year in detention pending trial following his Dec. 6, 1995, arrest, will be released in around June 2010 as part of the one-year period was counted as prison time served.

While he had pleaded not guilty to breach of trust, embezzlement, fraud and perjury in the scandal involving two now-defunct minor lenders -- Tokyo Kyowa Credit Association and Anzen Credit Bank -- the Supreme Court upheld the guilty verdict against him in December.

He had been out on bail since the ruling.

Yamaguchi has been convicted of colluding with the late Harunori Takahashi, president of Tokyo Kyowa, to arrange for 2.7 billion yen in illicit loans from the two lenders to a company run by his relatives.

Yamaguchi won 10 straight terms in the House of Representatives from Saitama Prefecture, having first been elected to the Lower House in 1967. He served as labor minister from 1984 to 1985 in the Cabinet of then Prime Minister Yasuhiro Nakasone.

He is the first former Diet member to be imprisoned for a crime committed while in office since Takanori Sakai, a former House of Representatives member, whose 32-month prison term was finalized in February 2005 for violation of the Political Funds Control Law and other offenses.