A senior Democratic lawmaker will push legislation this year to repeal a U.S. ban on Internet gambling that has hurt trade ties with the European Union, a congressional aide said.

The bill introduction should happen in the next month, a spokesman for House of Representatives Financial Services Committee Chairman Barney Frank said.

On Thursday, Reuters reported the EU could file a complaint about U.S. enforcement of the gambling ban at the World Trade Organization.

Mr. Frank will bring back legislation to repeal the UIGEA (Unlawful Internet Gambling Enforcement Act), the spokesman said, referring to a Republican-crafted bill passed in 2006 when the party controlled Congress and the White House.

Supporters of the ban argued offshore Internet gambling websites take billions of dollars out the U.S. economy, damage families and serve as vehicles for money laundering.

The law cost Europe's online gambling companies billions in lost market value as they were forced to retreat from one of their most lucrative markets. It barred businesses from knowingly accepting payments in connection with unlawful Internet gambling, including payments made through credit cards, electronic fund transfers and checks.

Against Frank's advice, the Bush administration finalized regulations late last year to implement the ban and gave companies until December 1 to comply.

Frank said the rules would burden the financial service industry at a time of economic crisis.

Many publicly traded European companies, including PartyGaming and 888.com, withdrew from the United States after Congress passed the ban, but they face possible criminal prosecution for activities before then.

Anurag Dikshit, a founder of PartyGaming, pleaded guilty in December to Internet gambling charges and agreed to pay $300 million in fines. He still faces possible jail time under a deferred sentencing arrangement. Other PartyGaming founders have not settled with the U.S. Justice Department.

EU industry officials said the pressure on Dikshit to make a deal showed the Justice Department had crossed a major line in its prosecution of cases.

The European Commission, acting on industry petition, began a formal investigation in March into whether Washington was singling out EU companies for enforcement actions while allowing U.S. online firms to operate freely.

Sources familiar with that investigation told Reuters in Brussels on Thursday they expect the investigators' report, initially due last year, to recommend action at the WTO when it is released next month.

Rather than move immediately to litigation, EU officials would use the report as leverage to seek a negotiated solution with the United States, they said.

(Editing by Eric Walsh)