KANDAHAR (AFP) - A bomb exploded in Afghanistan and killed two civilians while 28 Taliban and two Afghan soldiers died in clashes, the authorities said. The blast and the fighting on Tuesday took place in the south of the country, a Taliban stronghold where about 17,000 US troops are expected to deploy in the coming weeks to reinforce multinational troops fighting the Taliban. In Kandahar city, explosives fixed to a motorbike were detonated remotely as an Afghan army convoy passed, said the regional army commander, General Shair Mohammad Zazai. Two civilians were killed and three wounded, while five Afghan soldiers were hurt, he told AFP. Heavy fighting erupted in the neighbouring province of Helmand late Tuesday when gunmen attacked Afghan soldiers protecting police who were destroying illegal opium crops, the provincial government said. "Eighteen militants were killed and two Afghan army soldiers were martyred," provincial spokesman Daud Ahmadi told AFP. Two Westerners training the counternarcotics team were also wounded in fighting, he said. Helmand produces the bulk of Afghanistan's opium, which is used to make heroin in a drugs trade worth four billion dollars a year and one that earns Taliban millions of dollars, Afghan and US officials say. The authorities announced separately that the US-led coalition and Afghan troops had killed 10 Taliban in the southern province of Uruzgan Tuesday after coming under attack while on patrol. The forces called in air support after an initial gunbattle, which killed one fighter, a joint Press statement said. "Nine militants were killed and one fortified fighting position was destroyed during the strike," it said. In London, the British Defence Ministry (MoD) said three British soldiers were killed in southern Afghanistan as a result of an "enemy explosion" on Wednesday. "It is with great sadness that the Ministry of Defence has to announce the deaths of three soldiers from 1st Battalion The Rifles," it said in a statement, adding that their next of kin had been informed. Their deaths bring to 11 the total number of British soldiers killed in Afghanistan this year, and 148 since the US-led invasion of the country in late 2001.