SAO PAULO, Brazil (AP) — The Brazilian government has sent close to 9,000 troops to its borders with four neighbouring countries as part of a big two-week anti-crime operation.

Army, navy and air force personnel have been deployed along Brazil's frontiers with Argentina, Paraguay, Bolivia and Uruguay, the Defense Ministry said on its website yesterday.

The ministry said the operation, which began Monday, is aimed at stemming the inflow of drugs and arms and other contraband into Latin America's biggest nation.

One neighbor, Bolivia, is the world's number three cocaine-producing nation and officials there have estimated 92 per cent of that country's cocaine production heads to Brazil.

The area to which the troops have been sent includes the so-called Triple Border, the porous region where Brazil, Paraguay and Argentina converge and is home to drug and arms traffickers, smugglers and counterfeiters.

"Our main objective is to prevent Brazilian airspace from being used for illegal activities like drug trafficking and contraband," said Air Force Brigadier Joao Geraldo Ferreira Malta.

He said planes, helicopters and drones are being used in surveillance operations to identify suspects, provide support for ground troops and intercept planes that enter Brazilian territory illegally.

More than two tons of drugs, 300 vessels and 59 weapons were seized in four similar operations earlier this year and in 2010 in regions across Brazil. Four clandestine landing strips were destroyed and illegal lumber companies were closed down.

"This mobilisation along the border is a matter of self-defense," said David Fleischer, a political scientist at the University of Brasilia. "Brazil is invaded by drugs and clandestine arms shipments from the neighboring countries, mostly from Bolivia and Paraguay."

He said the operation could be effective but "not totally so."

To be really effective Brazil would have to have at least 50,000 troops spread out along the border, "but the country does not have the resources for that," he said.