At least 6,000 kg of drug-making chemicals and 4.5 tonnes of cocaine have been seized from eight laboratories near the Venezuela-Colombia border, officials said. "This has been one of the biggest operations in recent years," Interior Minister Tarek El Aissami said Thursday. The drugs belonged to Colombian "criminal groups", El Aissami said. Venezuela seized 66.3 tonnes of drugs in 2009, seven tonnes more than the previous year, the government said.