Farc calls for legal coca and marijuana plantations 6 February 2013 Last updated at 20:24 Colombia's Farc rebels have presented their proposals on land use at the peace talks, among them legalisation of coca and marijuana plantations. The document says the plants should have "industrial use for therapeutic and medicinal" or for "cultural ends." The left-wing group wants no more new oil and mining concessions, and the revocation of Amazon mining plans. Meanwhile, Colombia's police chief stepped up security at police stations after a wave of attacks by the Farc. General Jose Roberto Leon Riano said intelligence services had issued alerts and other measures had been taken to prevent further deaths. More than 10 policemen have been killed since the left-wing rebels suspended their ceasefire on 20 January. The wave of violence, with the government also stepping up their attacks on the rebels, is said to have heightened tensions in the peace talks. The Farc list with eight proposals for land use in Colombia was read out in Havana, Cuba, during the latest round of peace talks with the government. Besides marijuana and coca leaves, the Farc want to legalise the plantation of poppies. The Farc's chief negotiator, Ivan Marquez, read out the list before resuming the negotiations, in which land reform is the current issue at the table. " (The government has to) halt the policy of criminalisation and persecution, suspend air spraying and all the other forms of eradication which are generating negative social, environmental and economic impacts," he said. The left-wing group also wants the government to stop issuing new mining permits and oil exploration concessions. They say these activities should be decreased to free up an area of at least 20 million hectares (49 million acres) of land for farming. Among other land reform issues that had already been proposed by the Farc is a demand that 25 million hectares of land - more than 20% of the country - be handed over to the country's poor. The peace negotiations were launched in November in an attempt to end five decades of conflict. The government says it has cost the lives of more than 500,000 people.