Taliban insurgents used an eight-year-old girl carrying a bag of explosives to attack a police checkpost in central Afghanistan, the Afghan government said on Sunday, making her one of the youngest child bombers of the decade-old conflict.

The incident took place in Char Chino district of central Uruzgan province, the interior ministry said. "The insurgents handed over a bag with a homemade bomb to an eight-year-old girl and asked her to take it to police forces," it added.

"As the girl was getting close to the police, it exploded and killed the girl."

It was the latest in a string of unusual attacks on both sides of the Pakistan-Afghanistan border.

On Saturday a Taliban car bomber attacked a hospital in a remote district of eastern Logar province, damaging the maternity ward and killing between 20 and 35 people, according to reports.

Around the same time in north-western Pakistan, the Pakistani Taliban deployed a married couple who attacked a police station by blowing themselves up. Two burqa-clad figures made their way into a police station in Kolachi, near the Taliban hub of South Waziristan, pretending to want to lodge a complaint, police said.

Once inside they opened fire with guns and grenades, capturing hostages and triggering a five-hour siege that left 10 people dead. "This shows how much we hate Pakistani security institutions," Pakistani Taliban spokesman Ahsanullah Ahsan told Associated Press by telephone.

Both the Afghan and Pakistani Taliban have frequently used men disguised under burqas to mount suicide attacks but the use of women is rare.

The first genuine instance in Pakistan is believed to have occurred in Bajaur tribal agency late last year, when a female suicide bomber wearing a burqa attacked a UN food distribution centre, killing 45 people.

Last week in Dir district in north-western Pakistan, police defused a bomb strapped to a nine-year-old girl who said she had been kidnapped in Peshawar then set off walking towards a checkpost.

"They told me: 'You keep on reciting Qu'ranic verses till you push the button'," she said afterwards.

In Afghanistan, the Taliban have denied using child bombers, suggesting increased sensitivity to public opinion as peace talks with the US government loom.

The insurgency's conventional attacks are proving deadlier than ever. Four Nato soldiers were killed at the weekend, including two from Spain, while civilian casualties reached a decade-long high last May.

The violence comes days after Barack Obama announced plans to withdraw 33,000 American troops by September 2012, and undermines his claims to have militants "on the run".

The relentless Taliban assaults are fraying nerves among ordinary Afghans as

Nato prepares to transfer control of five urban centres, including most of Kabul, and two provinces next month.