UPDATE 4-Taliban suicide bomber kills 10 Afghan civilians

(Updates toll)

By Kamal Sadat

KHOST, Afghanistan, Aug 18 (Reuters) - A Taliban suicide bomber rammed an explosives-packed car into the gate of the main U.S. military base in southeastern Afghanistan on Monday, killing 10 civilians as the country observed its Independence Day.

The bombing, which wounded 13, comes at a time of heightened security as military and diplomatic officials warned intelligence reports indicated the al Qaeda-backed Taliban were planning a large attack to coincide with the independence day celebrations.

"The victims were all poor labourers and civilians," the governor of Khost province, Arsala Jamal, told Reuters. "This was a barbaric act carried out by the enemies of Afghanistan at a time of celebration of independence."

As security forces were dealing with the aftermath of the first blast, two more suicide bombers in another car approached, but were shot dead by police before they were able to detonate their explosives, Jamal said.

Violence has surged in Afghanistan this year as the Taliban step up their guerrilla and bombing campaign to oust the pro-Western Afghan government and drive out foreign troops.

The Taliban claimed responsibility for the blast at the base near the town of Khost, the main hub for U.S. and NATO-led operations in southeasern Afghanistan.

The Taliban detonated 77 suicide bombs by the end of July this year, slightly less than in the same time last year, and security forces thwarted another 76 suicide bomb attacks, a slightly greater success rate than in 2007, security experts say.