AMID the media frenzy and speculation over the disappearance of Air France's ill-fated Flight 447, the loss of two of the world's most prominent figures in the war on the illegal arms trade and international drug trafficking has been virtually overlooked.

Pablo Dreyfus, a 39-year-old Argentine who was travelling with his wife Ana Carolina Rodrigues aboard the doomed flight from Rio de Janeiro to Paris, had worked tirelessly with the Brazilian authorities to stem the flow of arms and ammunition that for years has fuelled the bloody turf wars waged by drug gangs in Rio's sprawling favelas.

Also travelling with Dreyfus on the doomed flight was his friend and colleague Ronald Dreyer, a Swiss diplomat and co-ordinator of the Geneva Declaration on Armed Violence who had worked with UN missions in El Salvador, Mozambique, Azerbaijan, Kosovo and Angola. Both men were consultants at the Small Arms Survey, an independent think tank based at Geneva's Graduate Institute of International Studies. The Survey said on its website that Dryer had helped mobilise the support of more than 100 countries to the cause of disarmament and development.

Buenos Aires-born Dreyfus had been living in Rio since 2002, where he and his sociologist wife worked with the Brazilian NGO Viva Rio.

"Pablo will be remembered as a gentle and sensitive man with an upbeat sense of humour," said the Small Arms Survey. "He displayed an intellectual curiosity and a determined work ethic that excited and enthused all who worked with him."

According to the International Action Network on Small Arms Control (IANSA), Dreyfus's work was instrumental in the introduction of landmark small arms legislation in Brazil in 2003. Under this legislation, an online link was created between army and police databases listing production, imports and exports of arms and ammunition in Brazil.

Dreyfus was an advocate of the stringent labelling of ammunition by weapons firms, arguing that by clearly identifying ammunition not only by its producer but also its purchaser, the likelihood of weapons being sourced by criminals from corrupt police or armed forces personnel is greatly reduced.

Though a Brazilian referendum on the right to bear arms was rejected in 2005, Viva Rio says the campaign should be considered a success because half a million weapons were voluntarily handed in to the authorities. Anti-gun activists put the referendum defeat down to fears criminals would circumvent the law and continue to gain access to small arms the usual way - through Paraguay and other bordering countries. This was not an irrational fear: until 2004, when Paraguay bowed to Brazilian pressure, even foreign tourists were allowed to purchase small arms simply by presenting a photocopy of their identity card. Dreyfus knew that many of the weapons from the so-called tri-border area between Brazil, Paraguay and Argentina were reaching Rio drug gangs.

When unidentified gunmen made off with a stash of hand grenades from an Argentine military garrison in 2006, Dreyfus deplored what he said was lax security at military depots across the world. "If a supermarket can keep control of the amount of peas it has in stock, surely a military organisation could and should be able to do the same with equal if not greater efficiency with its weapons," he said. "The key words are logisitics, control, security."

When Rio agents smashed a cell of drug traffickers who had sourced their weapons from the tri-border area, Dreyfus noted its leaders were prominent businessmen living in apartments in the plush Rio suburbs of Ipanema and S�£o Corrado, "not in the favelas".

In a recent report posted on the Brazilian website Comunidade Segura (Safe Community), Dreyfus noted that the Brazilian arms firm CBC (Companhia Brasileira de Cartuchos) had become one of the world's biggest ammunition producers by purchasing Germany's Metallwerk Elisenhutte Nassau (MEN) in 2007, and Sellier & Bellot (S&B) of the Czech Republic in March. This would not be particularly noteworthy but for the fact that CBC's exports had tapered off in recent years due to legislation restricting exports to Paraguay, arms that often found their way back into Brazil and on to the Rio drug gangs - the "boomerang effect", as Dreyfus called it. "The commercial export of weapons and ammunition from Brazil to the bordering countries stopped in 2001," wrote Dreyfus. "CBC lost commercial markets in Latin America, but Brazil won in public security."

However, manufacturers from other countries had moved in to fill the void, and before its purchase by CBC, S&B was already "one of the marks most currently apprehended" by Brazilian police. Dreyfus said that, in view of the fact the Czech Republic was bound by the EU Code of Conduct on weapons exports - which states that EU countries must "evaluate the existence of the risk that the armament can be diverted to undesirable final destinations", CBC should "consider the risk that some of these exports end up, via diversions, feeding violence in Brazil".

Though his focus was on Latin America, Dreyfus also advised the government of Mozambique and at the time of his death was preparing to do the same for the government of Angola, where stockpiles of weapons left over from the civil war continue to pose a security problem.

Dreyfus and Dreyer were on their way to Geneva to present the latest edition of the Small Arms Survey handbook, of which Dreyfus was a joint editor. It was to have been their latest step in their relentless fight against evil.