A Philippine appeals court overturned the 2006 rape conviction of a U.S. Marine and ordered his immediate release Thursday, setting off protests from activists.

A suburban Manila court convicted Lance Cpl. Daniel Smith of raping a Filipino woman in the company of fellow Marines at the former U.S. Subic Bay Naval base three years ago and sentenced him to life in prison. The case has become a rallying point for anti-American protests in the country.

The Philippine Court of Appeals overturned the ruling, indicating the sexual act was consensual.

"No evidence was introduced to show force, threat and intimidation applied by the accused," the court said in its 71-page decision, which is final.

It ordered the immediate release of Smith, 23, of St. Louis, Missouri, from his detention at the U.S. Embassy in Manila.

Interior Undersecretary Marius Corpus said Smith could be released within days, as soon as the process of notifying him and the embassy of the court's decision is complete.

After Smith was convicted, he was initially taken to a Philippine jail, but the U.S. argued he should be kept in American custody, citing the Visiting Forces Agreement, a 1999 accord that allows U.S. forces to conduct war exercises in the Philippines.

Washington said the accord entitles any accused U.S. service member to remain in American hands until all judicial proceedings are exhausted.