MEXICO CITY (Reuters) - Mexico City’s attorney general’s office has opened an investigation into the disappearance of journalist Mario Antonio Cañas, who was last seen on Friday, it said.

The attorney general’s office did not say if it suspected foul play. Advocacy group Reporters Without Borders has singled out Mexico as the most dangerous country for journalists in the Western Hemisphere.

Cañas, a 40-year-old radio journalist with Radio Formula, left his house in downtown Mexico City at around 2 p.m. on Friday and was last heard from some 4-1/2 hours later, the attorney general’s office said in a statement. He was presumably still in city at the time of his disappearance.

Formula Automotriz, a show about cars which Cañas hosted, tweeted images of the journalist asking for information about his whereabouts.

Since 2000, at least 114 journalists have been killed in Mexico, with 41 deaths since Enrique Pena Nieto became president in December 2012, advocacy group Article 19 says.