At least six people, including three policemen, have been killed in a suicide bombing in eastern Afghanistan.

A lorry filled with explosives was detonated outside a police compound in Puli Alam, capital of Logar province.

The Taliban claimed the bombing, the first major attack since the militants confirmed last week that their leader, Mullah Omar, was dead.

It came as an Afghan military helicopter crashed in the south, causing a number of casualties.

The cause of the crash, in Zabul province, is unclear and the number of casualties has not been confirmed but local officials say as many as 17 people may have been killed.

The blast in Logar, near the capital Kabul, was the latest in a wave of militant assaults this year since most foreign troops withdrew from Afghanistan.

"The bomb was huge and it was carried by a mini-truck," said provincial Governor Aleem Fedaee.

"It inflicted a lot of damage to the civilians and broke windows even a kilometre away."

At least 13 people were wounded, medical officials said.

In a statement, the Taliban said it had targeted military and paramilitary units.

Last week's Taliban statement did not say where, when or how Mullah Omar had died.

The Afghan government said the Taliban leader had died in hospital in the Pakistani city of Karachi two years ago.

However, Pakistan has always denied that he was in the country.

Mullah Akhtar Mansour, Mullah Omar's deputy, has replaced him, Taliban sources have said, amid reports his appointment has caused deep divisions in the movement.