Costa Rican authorities have seized 4 tons of cocaine this year at a single crossing point on the Nicaraguan border, in a sign that overland shipping routes remain important despite Costa Rica’s efforts to tighten security on its land borders.

Costa Rica’s Security Ministry said that 4 tons of the drug have been seized in 2012 at the Peñas Blancas crossing, close to the Pacific coast, reports EFE.

The most recent confiscation took place on April 7, when Costa Rican police found 256 kilos of cocaine hidden in the tires of a truck driven by a Salvadoran national, who was reportedly heading to El Salvador.

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Drug traffickers are increasingly shipping their product through Costa Rica, which confiscated its highest-ever amount of narcotics in 2011, at more than 10 tons. Much of the drug trade in Costa Rica is thought to be controlled by the Mexican Sinaloa Cartel.

The 4 tons seized this year at Peñas Blancas means that the crossing point, which lies on the Pan-American Highway, may be the most important route for land shipments of drugs passing through the country. In the last six months of 2011, the Costa Rican authorities seized just over 4 tons in the country as a whole. Peñas Blancas has seen high cocaine seizures for some time; in 2009, nearly 3 tons of cocaine were confiscated there.

The high rate of seizures suggest that overland routes through Costa Rica remain important, despite reports that tighter security on the country’s southern and northern borders had encouraged traffickers to move away from land routes and ship more drugs by air and sea.