Nine die in Afghan suicide blast

At least nine people have been killed when a suicide bomber rammed a car into the gate of a US base in eastern Afghanistan, officials said.

The dead were all Afghan civilians. Thirteen others were wounded in the blast in Khost province.

The attack comes on a day when Afghanistan is celebrating its independence day.

A top US general has warned that militants are planning attacks to coincide with the festivities.

A planned address by President Hamid Karzai has been called off and the UN staff have been told to work from home.

Tight security

Khost governor, Arsala Jamal, told Reuters news agency that the victims of Monday morning's attack were "poor labourers and civilians".

Police shot dead two more suicide bombers before they could detonate explosives in another car, he said.

Most of the troops deployed in Khost are American.

The attack comes as Afghanistan marks its independence from Britain 89 years ago.

Meanwhile, a senior US general in Afghanistan Maj Gen Jeffrey J Schloesser is reported to have warned of "credible intelligence" reports showing that militants may attack public gatherings during the celebrations.

Thousands of soldiers have been deployed in the capital, Kabul, and police check posts have been set at nearly every intersection in the city and the main entry points into the capital.

Violence has surged in Afghanistan this year with the Taleban often targeting international and Afghan troops.