WASHINGTON (Reuters) - The U.S. government has been bringing more criminal tax prosecutions against Americans under President Barack Obama than under President George W. Bush, with a surge in tax refund fraud partly to blame, a non-partisan watchdog said on Tuesday.

Transactional Records Access Clearinghouse (TRAC) said in a report that it found that under Obama the average annual number of tax crime prosecutions sought by the Justice Department has been 1,568, versus 1,303 under Bush.

Most criminal tax cases involve alleged fraud and tax-dodging. The Justice Department is fighting an upswing in tax crimes, and tax refund fraud, stemming from fake identity documents, the report said.

In the Obama years, case recommendations brought by the Internal Revenue Service to the Justice Department have soared by 23.4 percent compared to the Bush years, TRAC said.

TRAC is a Syracuse University research group in New York state. It said it obtained the information from Freedom of Information Act requests.

"This is certainly reflecting a get-tough attitude" at the IRS, despite budget cuts, said Susan Long, TRAC co-director.

In 2013, Justice sought 2,010 new criminal tax prosecutions, the largest number since 1997, TRAC data show. The number of prosecutions sought in 2012 was 1,539.

(Reporting by Patrick Temple-West; Editing by Kevin Drawbaugh and Tom Brown)