JERUSALEM (Reuters) - Israeli Prime Minister Ehud Olmert admitted on Thursday taking cash from a U.S. businessman but resisted calls to resign over a police investigation into alleged hefty bribes over almost a decade.

As Israelis enjoyed festivities marking Independence Day and the 60th anniversary of the founding of their state, police lifted a week-old media gag order and announced details of accusations that sparked opposition calls for Olmert to quit.

He said he would resign only if he were formally indicted.

Whether he goes or not, doubt over his future is likely to upset his faltering, U.S.-sponsored peace negotiations with the Palestinians and will cast a heavy cloud over next week's celebratory visit to Israel by U.S. President George W. Bush.