UPDATE 1-Rival Bangladesh parties join forces to press for poll

(Adds U.S. official's comments)

By Anis Ahmed

DHAKA, Feb 3 (Reuters) - Bangladesh's normally feuding main political parties have struck an informal deal to join forces to press the army-backed interim government to hold elections earlier than scheduled.

The Awami League and Bangladesh Nationalist Party (BNP), led respectively by detained former prime ministers Sheikh Hasina and Begum Khaleda Zia, are also uniting to press the government to release the two women and drop various graft charges against them.

"They are trying to unite on minimum understandings," said Professor Ataur Rahman, president of the Bangladesh Political Science Association, an independent think tank.

The first clue to the new rapprochement came on Saturday when the Awami League's acting chief, Zillur Rahman, called for the release of both women, who, despite uniting to overthrow military ruler Mohammed Ershad 15 years ago, fell out soon afterwards and are reputed not to have spoken to each other since.

Supporters of both parties have frequently clashed over the years -- often with bloody consequences -- and political violence was one of the main reasons the interim government gave for imposing emergency rule a year ago.

Both Hasina and Khaleda are facing multiple charges of graft and extortion and, if convicted, will lose their right to contest elections, which the government promised to hold before the end of this year.

The Awami League and BNP want elections to be held by July.