LIMA, Peru, Nov 8 (Reuters) - In a massive raid on the central jungle drug heartland, Peruvian police seized 1,435 pounds (651 kg) of cocaine and destroyed 39 makeshift drug laboratories, the government said on Saturday. The operation, dubbed "Iron 2003," has been under way in the Monzon valley since Thursday and involves 600 police, the Interior Ministry said in a statement. Peru is the world's second-largest cocaine producer, after Colombia. Interior Minister Fernando Rospigliosi earlier this week justified the start of the swoop saying, "The Monzon valley has been a no-man's land for years. There have long been no police there and drugs traffickers have been able to come and go as they please." The operation, involving 11 armored helicopters, was continuing on Saturday but the Interior Ministry said five people who had been working in the cocaine processing sites had been arrested and 10 stolen vehicles had been recovered. Police said the drugs seized were in the form of basic cocaine paste. Media reports said some locals complained about the scale of the operation and the use of tear gas, according to El Comercio daily. Peru is engaged in a tough battle to reach its 2003 goal of wiping out 19,800 acres (8,000 hectares) of coca crops -- the raw material for cocaine. The Andean country has 89,000 acres (36,000 hectares) of coca of which an estimated 29,650 acres (12,000 hectares) supply coca for legal uses such as infusions and the traditional practice of chewing the leaf as a stimulant. The rest is sold into the illegal cocaine trade. "We don't know how long this operation will go on. It will last until we meet our objectives. But this is definitely a first step toward reestablishing the presence of the state in this area," Rospigliosi said in the statement. In a separate operation on Saturday, an army patrol in a different part of the central jungle clashed with rebels of the Shining Path group, the Defense Ministry said. Three rebels were killed and one officer injured and the army seized several guns, ammunition and propaganda. Shining Path, at its height one of Latin America's bloodiest insurgencies, has died down since the 1992 capture of its leader but a few hundred rebels, whom officials say are often involved in the drugs trade, remain holed up in central jungle and Andean areas and have staged recent attacks.