A suicide bomb killed at least four policemen on Sunday in the southern Afghan city of Kandahar, local police said. The escalation of violence in Afghanistan this year, the bloodiest period since the Taliban was ousted in 2001, has raised fears about the prospects of stability in the country despite an increasing number of foreign troops. A Reuters witness at the scene said the attacker detonated his device in front of the Chinese hospital in the capital of Kandahar province. Removed from power in 2001, the Taliban largely rely on suicide and roadside bomb attacks as part of their campaign to topple the Western-backed government and drive out foreign troops under the command of NATO and the US military.