BRASILIA (Reuters) - In a continued roundup of suspects who could have links to terrorism ahead of the Rio Olympics, Brazilian police said Friday they had arrested a Lebanese man who was a former member of the militant group Hezbollah and wanted for drug trafficking.

Fadi Hassan Nabha, 42, was arrested late Thursday at his home in Caieiras, a suburb of Sao Paulo, on orders from the Justice Ministry that has been seeking to expel him from Brazil, a spokesman for the military police said.

"We have been looking for him since May because he was wanted for drug traffic, not terrorism," the spokesman Augusto Roque told Reuters.

Nabha, who has been on Interpol's wanted list since 2013 for drug trafficking, told police he served in Hezbollah's special forces for two years and had weapons and explosives training, Roque said. No weapons were found in his home, only false identity papers, Roque added.

Brazil does not consider Hezbollah a terrorist organization. While Nabha was not arrested on suspicion of terrorism, he was picked up a week before the Olympic Games open in Rio amid heightened security measures and concerns about Islamist extremist-inspired violence following attacks in European cities.

Brazilian authorities have particularly stepped up arrests and monitoring of anyone suspected of links to the Islamic State militant group as opposed to Hezbollah, a separate organization whose support comes from a different geographic region and a different branch of Islam.

"The government is on full alert and there have been preventive arrests of suspect elements," Brazil's interim President Michel Temer told foreign reporters on Friday.

Temer said no terrorist group has been discovered operating in Brazil but there was concern "a madman might do something."

On July 21, Brazil arrested 10 people suspected of belonging to a poorly organized group that supports Islamic State and had begun discussing terrorist acts during the Olympic Games. It has subsequently detained two more suspects in that case.

On Wednesday, police arrested a man, Chaer Kalaoun, in the state of Rio on allegations of posting apologies for Islamic State after monitoring his online activity.

Kalaoun's lawyer denied he had any ties to terrorist groups and said police had also detained him before Brazil hosted the World Cup in 2014 on charges of illegal possession of firearms.

South America's first Olympics kicks off Aug. 5 with some 500,000 visitors expected to travel to Brazil. Authorities are on high alert following attacks in France and Germany in recent weeks.

(Reporting by Anthony Boadle; Editing by Bernadette Baum and Mary Milliken)