(Bloomberg) ? Democratic lawmakers asked Homeland Security Secretary Tom Ridge to reconsider awarding a contract worth as much as $10 billion to a group led by Accenture Ltd., which is based in Bermuda, a haven from US taxes.

Representative Rosa DeLauro, a Connecticut Democrat, and three other House members said in a letter that Accenture's tax status helped its group beat out offers by US-based companies, including Computer Sciences Corp. and Lockheed Martin Corp.

"Accenture has not only cost the US treasury millions of dollars which could be put to use in improving our homeland security, but they have placed loyal US companies at a permanent competitive disadvantage," the letter said.

The lawmakers are among the members of Congress seeking to close what they call a tax-haven loophole and to deny government contracts to US companies that have set up headquarters in low- tax countries, such as Bermuda, the Cayman Islands and Barbados. Democratic Representatives Lloyd Doggett of Texas, Louise Slaughter of New York and Marion Berry of Arkansas also signed the letter to Ridge. Accenture spokeswoman Roxanne Taylor said the company is being unfairly targeted by the lawmakers. Accenture never was an American company; rather it was a series of international partnerships operating through a Swiss entity before it was incorporated in Bermuda, she said in an e-mail.

A spokesman for Representative Tom Davis, a Virginia Republican and chairman of the Government Reform Committee, called the effort by the four Democrats "purely political."

"Blocking companies from bidding on government contracts just because they are incorporated offshore reflects a rejection of the free market principles of the federal procurement system ? principles that allow the taxpayer to get the best services or goods at the lowest price," the spokesman, David Marin, said.

Accenture pays US taxes on income generated by its US operations. Its US-based subsidiary employs about 25,000 workers and would handle the homeland security contract, Taylor said.

Under the ten-year contract, Accenture's group will develop a system to collect and share data on foreigners entering the US as part of a programme to protect against terrorism.

The Homeland Security Department saw no conflict in awarding the contract to a Bermuda-based company, Undersecretary of Border and Transportation Security Asa Hutchinson said yesterday.

Federal procurement records show Accenture in 2002 had federal contracts worth about $450 million, of which $250 million were related to military or homeland security functions.