The Brazilian authorities are trying to locate a former Guantanamo prisoner who is believed to have entered the country illegally after disappearing from Uruguay.

Abu Wa’el Dhiab, a Syrian national, was released in Uruguay along with five other former Guantanamo inmates in 2014.

But his whereabouts are now unclear. Uruguay's government says that he has crossed the border into Brazil; the Brazilian authorities say they have no record of Dhiab entering legally.

Federal police are now searching for the 44-year-old, who spent 12 years in Guantanamo.

According to police sources quoted by the Brazilian newspaper O Globo, Dhiab had tried to enter Brazil on three previous occasions. He was refused entry each time because his name appears on an international database of suspected terrorists.

The Olympic Games are due to open in Rio de Janeiro on August 5.

Avianca Airlines, a Brazilian carrier based in São Paulo, has alerted staff that Dhiab may try to fly using a false passport.

The Syrian was captured by the US military in Afghanistan in 2002 and accused of forming part of an al-Qaeda terrorist cell. But he was never formally charged with any offence and cleared for release in 2009.

Belela Herrera, a former Uruguayan deputy foreign minister now working as a human rights activist, said the reaction to Dhiab's disappearance was "crazy". She told Associated Press news agency that no case had ever been brought against him and it was wrong to link him to terrorism.