PULI ALAM, Afghanistan: A roadside bomb ripped through a minibus in the central Afghan province of Wardak on Tuesday, killing five civilians, an official said.

"A mine planted by the enemies of Afghanistan detonated under a civilian minibus. Five civilians including women and children have been killed. Two others are injured," said provincial government spokesman Sahidullah Shahid.

Four other passengers survived the explosion in the restive province's Sayed Abad district, he said.

The blast came a day after another roadside bomb killed five people in northern Afghanistan and a week after twin suicide bombings killed 23 people in the south.

Taliban insurgents regularly use improvised roadside bombs to target Afghan and Western military forces, but they often kill civilians who use the same roads.

For the past five years the number of civilians killed in the war has risen steadily, reaching a record 3,021 in 2011 -- the vast majority caused by insurgents, the United Nations says.

The phrase "enemies of Afghanistan" is used by Afghan officials to refer to the Taliban, which is still fighting a bitter insurgency more than a decade after being toppled from power by the 2001 US-led invasion.