Former US vice president Al Gore was the subject of a 2006 sex crime investigation but the inquiry stalled after his accuser declined to be interviewed by police, prosecutors said on Wednesday.
Michael Schrunk, District Attorney for Multnomah County in northwestern Oregon state, confirmed in a prepared statement that Gore had been accused of "unwanted sexual contact" in late 2006 and early 2007.
"We were told the woman was not willing to be interviewed by the Portland Police Bureau and did not want a criminal investigation to proceed," Schrunk said in the statement.
The disclosure follows revelations in the National Enquirer tabloid about a masseuse who complained of a sexual advances by Gore during an incident at a Portland Hotel in 2006.
Schrunk said police in Portland had carried out a further investigation into the incident in 2009.
"If the complainant and the Portland Police Bureau wish to pursue the possibility of a criminal prosecution, additional investigation by the Bureau will be necessary and will be discussed with the Portland Police Bureau," the prosecutor said.
Gore, 62, winner of the Nobel Peace Prize in 2007, earlier this month confirmed he was separating from wife Tipper after four decades of marriage, an announcement that caused widespread surprise among political observers.