Taliban gunmen have shot and killed the head of the Independent Election Commission in Afghanistan's northern Kunduz province.

It comes a day after he warned that deteriorating security threatened next year's presidential elections.

Amanullah Aman began his work during the first presidential election in 2004. He was the commission's first member to be assassinated since it started work in May.

The Taliban claimed responsibility.

The group's elusive leader Mullah Mohammad Omar sent a message to the Afghan people in August rejecting the elections and vowing to fight until foreign troops leave.

Most troops are due to withdraw by the end of next year.

"Two gunmen on a motorbike opened fire on Engineer Aman this morning," said Kunduz police spokesman Sayed Sarwar Hussaini.

"Aman was on his way to work when he was attacked in Kunduz city."

Mr Aman died of his wounds in hospital.

Earlier this week, he had said worsening security made fraud, such as stuffing ballot boxes, a serious threat to the process.

The three-week period to register candidates for the April 2014 election opened on Monday, but no one has yet stepped forward.

The vote will be a key test for Afghanistan as it prepares for the departure of Western forces amidst a resurgent Taliban-led insurgency.

Fears of attacks may deter many voters from going to polling stations, while remote districts in insurgent strongholds are virtually impossible for election officials to reach.

A shortage of female security officers could keep women from voting.

The IEC last month said only 2,000 women were available - of the 12,000 required - to carry out body searches outside polling stations set aside specially for women.