* Karzai rival attracts biggest crowd of campaign * Former president ambushed, Taliban attacks spread * Three British troops, one American killed in south (Adds British troops killed, paragraph 10, U.S. death, 11) By David Fox MAZAR-I-SHARIF, Afghanistan, Aug 13 (Reuters) - Afghan President Hamid Karzai's main rival drew a huge crowd to a rally on Thursday but violence still loomed as a threat, with a former leader escaping an assassination attempt a week before the vote. Tens of thousands of supporters greeted Abdullah Abdullah, Karzai's former foreign minister, in his stronghold in the northern city of Mazar-i-Sharif, the biggest rally so far before the Aug. 20 poll. "Don't think that this is finished. Don't listen to what others might tell you, this election is very close," Abdullah told supporters at the blue-tiled Shrine of Hazrat Ali. Karzai needs to win more than 50 percent of the vote to avoid a run-off against the second-placed challenger. A U.S.-funded poll by a little-known Washington firm published earlier this week gave Karzai 45 percent to Abdullah's 25. The Taliban have vowed to disrupt the election and violence, especially in Karzai's ethnic Pashtun power base in the south, also looms as another threat to the man who has ruled Afghanistan since 2001 and won the country's first direct election in 2004. Poor voter turnout over security fears, especially in the south, could eat into Karzai's support base and increase the chances of a second round run-off vote in October, when other challengers in the 36-strong field could unite behind Karzai. Abdullah is half Pashtun, Afghanistan's largest ethnic group, but draws most of his support from ethnic Tajiks. The crowd in Mazar-i-Sharif, about 300 kms (190 miles) north of Kabul, swelled to about 50,000 supporters wearing blue caps and T-shirts bearing Abdullah's lightly bearded image as his convoy drove to the shrine. Some were trampled in the crush. TALIBAN'S REACH SPREADS Violence this year had reached its worst levels since the Taliban were ousted by U.S.-backed Afghan forces in 2001 and escalated further after U.S. and British forces launched major operations in southern Helmand province. Three British soldiers were killed by a roadside bomb in Helmand on Thursday, the Ministry of Defence in London said. A total of 199 British soldiers have been killed in the Afghanistan war, at least 30 since the Helmand offensives began. A U.S. service member was also killed by "direct fire" in the south on Thursday, the U.S. military said. No details were available. The operations in Helmand were the first under U.S. President Barack Obama's new regional strategy to defeat the Taliban and stabilise Afghanistan. But the Taliban have hit back, their reach spreading out of their heartland in the south and east into the previously more peaceful north and west, and even to the outskirts of Kabul. Former Afghan President Burhanuddin Rabbani, one of Abdullah's main supporters, survived a Taliban ambush on Thursday in northern Kunduz province, where militants clashed with police for a second night. Rabbani was not hurt. Mohammad Qasim Fahim, one of Karzai's running mates, also survived an assassination attempt in Kunduz last month. Fahim was the military leader of the U.S.-backed guerrillas known as the Northern Alliance that helped topple the Taliban, with Rabbani the movement's political chief. Rabbani was travelling on a Kunduz road when the Taliban ambushed him with rocket-propelled grenades and gunfire, said Ali Abad district chief Habibullah Mohtashim. Rabbani and others in the convoy were unhurt. Three Taliban fighters were killed in the ensuing clash with Rabbani's bodyguards, Mohtashim said. The Taliban claimed responsibility. In another part of Kunduz, three policemen and eight insurgents died in gunbattles. On Wednesday, insurgents killed a district police chief, triggering battles that raged until dawn. In Helmand, a van drove over a roadside bomb, killing at least nine people, the Interior Ministry said. Local police put the death toll at 11. Helmand was chosen as the starting point of Obama's strategy in part because it is Afghanistan's biggest source of the opium poppies that largely fund the insurgency. In neighbouring Kandahar, another big opium centre, Karzai's half-brother Ahmad Wali Karzai denied a report in German magazine Stern that British special forces last month found several tonnes of opium on land he owned, saying it was an attempt to discredit the president before the poll. "This is the time of the election. They are just doing this to hurt the president, that's all," Ahmad Wali Karzai told Reuters by telephone. U.S., British and other allied forces have suffered their worst losses of the 8-year-old war with more than 103 killed since the operations to drive the Taliban out of populated areas in Helmand were launched on July 2. Some 30,000 additional U.S. troops have arrived in Afghanistan this year, bringing the total Western force to more than 100,000 for the first time, including 62,000 Americans. (Additional reporting by Mohammad Hamid in Kunduz and Peter Graff and Sayed Salahuddin in Kabul; Writing by Paul Tait; Editing by Janet Lawrence) (For more on Afghanistan, click on [ID:nAFPAK]) (For more Reuters coverage of Afghanistan and Pakistan, see: http://www.reuters.com/news/globalcoverage/afghanistanpakistan)
Mourners react as the coffins of four soldiers killed in Afghanistan are driven though the streets of Wootton Bassett, in Wiltshire in south west England August 13, 2009. Four British soldiers ...
