KABUL (Reuters) An Afghan soldier fired a rocket-propelled grenade at an outpost manned by French and Afghan troops in Kapisa province, north of the capital, Kabul, but caused no casualties, the French military said on Tuesday. The attack was the latest in a recent spate by rogue police and soldiers, underlining pressure as NATO-led troops try to train Afghan forces to allow them to take over security of the country and allow foreign troops to start withdrawing. It missed and nobody was injured. The soldier fled and we havent caught him, said French Armed Forces spokesman Colonel Thierry Burkhard. The soldier joined the Taliban after the attack, the insurgent group said in a text message sent to a Reuters phone. Two Spanish police and an interpreter were killed by an Afghan policeman they were training in August, at a remote base in the countrys northwest. In July, an Afghan soldier killed three British Gurkha soldiers and a week later two US contractors were killed by an Afghan soldier inside a military base in the north. Afghan authorities began tighter vetting of recruits after a renegade soldier killed five British troops last year. The former head of the UN Office on Drugs and Crime, Antonio Maria Costa, this week was quoted saying the Taliban had formed sleeper cells within Afghanistans security forces.