A bomb killed three US soldiers in southern Afghanistan on Friday, hours after a suicide bomber killed 10 Afghan civilians and two Afghan policemen in a separate attack in the south, officials said. The attacks bring the toll of US soldiers killed in southern Afghanistan to five in less than 24 hours. The US military is planning to send up to 30,000 extra troops to the south this year to try to stem the virulent Taliban insurgency. The US soldiers were killed when a home-made bomb exploded in the Tarnak va Jaldak district of Zabul province which borders Kandahar province, where two US soldiers were killed on Thursday, NATO said. Earlier on Friday more than 10 civilians, one senior policeman and his bodyguard were killed and at least 20 civilians were wounded in a suicide bomb attack in a market in Nimroz province, also in south Afghanistan, the governor of Nimroz said. The Nimroz blast toll could rise further as casualties are pulled from the rubble of four shops destroyed by the explosion in Zaranj, the capital of Nimroz, Governor Ghulam Dastegir-Azad said. A Taliban spokesman said they had carried out the Nimroz attack, which he said killed eight policemen, including two police commanders. The Taliban often exaggerate the number of security forces they have killed.