“We know that we was set free by his captors, but we don’t have further

details,” the Colombian intelligence spokesman told AFP on Tuesday.

The 69-year-old engineer was snatched by guerrillas from the Revolutionary Armed Forces of Colombia in May 2007.

In February, Sweden’s ambassador to Colombia appealed for his release and

recalled that he was the only Swedish hostage in the world.

According to the Colombian intelligence agency, FARC guerillas had demanded $5 million for Larsson’s release.

Larsson’s health “is fragile” and is being reviewed by a medical team in Monteria, said the intelligence spokesman.

The jungle-based FARC have fought a four-decade long struggle against the Colombian government, but are classed as a terrorist organization by Washington and the European Union.

The group — thought to consist of up to 10,000 fighters — is believed to hold more than 700 hostages, actions which have heavily eroded public support for the organization.