UPDATE 3-Foreign tax havens targeted in U.S. bills

* Tax haven crackdown bills introduced in Senate and House

* Senate bill co-sponsored last year by then Senator Obama

* Patenting of tax-dodging schemes would be banned (Adds bills introduced, House bill, Swiss minister comments)

By Kevin Drawbaugh

WASHINGTON, March 2 (Reuters) - Offshore tax havens used by rich Americans in Switzerland, the Cayman Islands and other nations are targeted for shutdown by bills offered on Monday by Democrats in both chambers of the U.S. Congress.

The Senate bill expands on one co-sponsored last year by then-Senator Barack Obama and Senator Carl Levin, who has sought a broad crackdown on tax dodgers estimated to deprive the U.S. government of more than $100 billion a year.

A thriving business in tax evasion developed in recent years on Wall Street among consulting firms, hedge funds and other elite financial players. Some purveyors even sought patent protection for their off-the-shelf schemes.

The Levin bill would ban patenting of tax avoidance plans, target dozens of offshore "secrecy jurisdictions" for attention, and put a greater burden on taxpayers to show that their tax arrangements are legitimate.

"Offshore tax haven and tax shelter abuses are undermining the integrity of our tax system," said Levin, of Michigan, in a statement. "We cannot tolerate $100 billion in offshore tax abuses burning a hole through our budget each year.