JOHANNESBURG — France, the United States, and some other countries have advised their nationals to avoid travel to a tourist island in Madagascar after the deaths of two Europeans and a local man who were attacked by a mob that reportedly suspected them of organ-trafficking.

France has confirmed that a French national was among the dead and has urged local authorities to clarify the circumstances of what happened on the island of Nosy Be on Thursday morning. The Italian news agency ANSA said an Italian with both Italian and French passports was also killed.
 

The attack happened after residents discovered a boy's mutilated body on a beach, according to media in Madagascar. The reports cite witnesses as saying the two Europeans were paraded through villages, beaten and burned on a beach.
 

There had been reports of "arson, looting and the mob killing of two foreign suspects held in police custody," sait the U.S. Embassy in Madagascar.
 

Organ-trafficking involves the illegal trade of kidneys and other human organs for transplants. It is hard to compile reliable data on the extent of the murky trade, which is shrouded in rumor.
 

There are occasional prosecutions, though. This year, a court in Kosovo found two citizens guilty of human trafficking and organized crime in a major trial against people suspected of running an international organ trafficking ring that took kidneys from poor donors lured by financial promises.
 

The deadly riots were another blow to Madagascar's tourism industry, which has suffered because of political tension in the Indian Ocean country, one of the world's poorest.

Madagascar, which has 20 million people, holds presidential elections on Oct. 25 amid a protracted political crisis. President Andry Rajoelina overthrew his predecessor in 2009, but Madagascar's special electoral court has barred him from running in the election as part of measures to restore stability.
 

Responding to the riots in Nosy Be, France's foreign ministry urged local authorities to secure the safety of French citizens, urged its nationals living there to stay at home and advised those planning to visit the island to postpone their trip. About 700 French citizens living on Nosy Be are registered with the French embassy. The French school there has temporarily closed.
 

Britain's Foreign Office also advised against all travel to Nosy Be, a major tourist destination near the northwest coast of Madagascar.
 

"British nationals currently living in Nosy Be should stay indoors and follow local security advice," it said in a statement.
 

Swedish authorities said crowds in Nosy Be should be avoided and travelers should monitor the situation via local media.
 

Authorities in Madagascar appealed for calm and sent police reinforcements to the island.
 

Nosy Be, which means "big island" in Malagasy, the national language, has direct flights to some European destinations. Tourists who stray from the island's beaches are offered tours of rum distilleries, sugar cane fields, volcanic lakes and the colonial-era town of Hell-Ville.