A group firm of major U.S. investment fund Lone Star has allegedly failed to declare some ¥14 billion in income earned in Japan for two years through 2003, sources said Monday.

Tax authorities are expected to impose some ¥5 billion in back taxes on the Lone Star-affiliated investment company, which is based in the Bermuda Islands, the sources said.

The investment company, whose name was not disclosed by the sources, has refused to respond to a request by the National Tax Agency to declare the income, they said.

The trail started in 2001, when Lone Star acquired Tokyo Star Bank, the successor to Tokyo Sowa Bank, which collapsed in 1999 under the weight of bad loans.

Earlier in March, Japanese investment fund Advantage Partners announced that its friendly buyout bid for Tokyo Star Bank was successful, with shareholders holding a combined 98.31 percent stake in the bank tendering their shares.