KANDAHAR (AFP) The chief of a district key to Nato counter-insurgency efforts in Afghanistan was killed by a car bomb on Tuesday, as four alliance troops died in attacks across the country. The district chief, his son and a bodyguard were killed by the remote control blast in southern Afghanistans Taliban heartland of Kandahar city, deputy provincial police chief Fazil Ahmad Sherzad told AFP. The attack, near a roundabout in the city as the district chief was on his way home, was condemned by President Hamid Karzai as a plot by the enemies of Afghanistan. An AFP reporter saw three charred bodies being removed from a burning car in the city, birthplace of the Taliban movement where many of the 30,000 troops US President Barack Obama ordered to Afghanistan late last year are headed. Abdul Jabar, the district chief of Arghandab, one of his sons and a bodyguard were killed when a car bomb exploded near their vehicle in Kandahar city district one, Sherzad said. Tuesdays attacks came as the chief of Sayedabad district in Wardak province, south of the capital Kabul, was kidnapped by two armed men while driving to his office, deputy provincial police chief Ahmad Ali Rasekh said. The attack against the district chief came as four Nato troops - two British, one American and one Polish - were killed in a series of incidents in eastern and southern Afghanistan. Up to 12 policemen, five rebels and two civilians were also killed in a wave of violence overnight Monday across the country, the interior ministry and police officials said. Sayeed Ansari, spokesman for the Afghan spy agency the National Directorate of Security, announced in Kabul Tuesday that three militants had been arrested for a series of attacks that killed a pair of Afghan soldiers.