The case against the marines stirred up anti-US feeling
A Philippine woman who secured a rape conviction against a US marine more than two years ago has now suggested the sex was consensual.
A statement from the woman, known as Nicole, says she is tormented by guilt.
Lance Corporal Daniel Smith was sentenced to 40 years in jail. He is currently being detained at the US embassy in Manila, pending an appeal.
The case had stirred anti-American feelings in the Philippines, and strained ties between the two nations.
"My conscience continues to bother me," Nicole wrote, "realising that I may have in fact been so friendly and intimate with Daniel Smith at the Neptune Club, that he was led to believe that I was amenable to having sex or that we simply just got carried away."
Nicole had previously testified that Smith took advantage of her drunkenness to rape her in a parked van.
The incident was alleged to have occurred after the pair, who had just met, drank and danced together in Subic Bay, the site of a former US naval base.
Smith insisted throughout the trial that he was innocent and the sexual encounter had been consensual.
Following his December 2006 conviction, he was transferred to the US embassy in Manila, in a move that was fiercely contested by Nicole's supporters.
They were incensed to see the marine escape the harsh realities of Philippine jails.
The embassy insisted that under the Visiting Forces Agreement, which regulates the presence of American counter-terrorism troops in the Philippines, the US was entitled to retain custody of Smith until the end of the legal process.
The case strained relations between the two countries, and led to vocal calls in the Philippines for the abrogation of the VFA.
Nicole's new version of events has shattered certainties in the case - although some Philippine left-wing activists have suggested both governments may have leaned on Nicole to change her story in order to keep the VFA in existence.
Philippine Justice Secretary Raul Gonzales expressed annoyance at the latest turn of events.
He said Nicole's allegations had affected the country's foreign policy and suggested she could be charged with perjury.
But Nicole's whereabouts are unclear.
Her lawyer said she had been informed by her client's mother that Nicole had now emigrated to the United States and no longer wished to talk.