A suicide bomber has killed the governor of eastern Afghanistan's Paktia province - the highest-ranking official to die in the insurgency.
Mr Taniwal was an academic with Australian citizenship
The governor, Abdul Hakim Taniwal, was attacked outside his office. The Taleban said it carried out the attack.
He is described as an academic who wanted to end Afghan gun culture.
Meanwhile in southern Kandahar province Nato and Afghan forces say they have killed 94 Taleban fighters in overnight battles during a major offensive.
It is part of Operation Medusa, which Nato says has killed 420 insurgents since it began more than a week ago. The Taleban disputes this figure.
Mr Taniwal was in a car leaving his office in the provincial capital Gardez when he was targeted by the bomber with explosives attached to his body.
A bodyguard and driver were also killed in the attack, for which the Taleban has claimed responsibility.
Governor Taniwal is the highest-ranking Afghan official to be killed since the Taleban insurgency began.
Afghan President Hamid Karzai said he was "deeply saddened" by the governor's death.
"Mr Taniwal was a patriot, a man of both action and academic achievements. He was also a personal friend of mine, who returned from abroad to serve his nation," he said in a statement.
The head of the UN assistance operation in Gardez, Thomas Gregg, told the BBC World Service's Newshour programme the governor's death was a major setback.
"In many ways, it was Governor Taniwal's positive attributes that made him a target," Thomas Gregg said.
"It's a ... very sad day for both Afghanistan and the international community. He was a fine leader."
The BBC's Grant Ferrett says Mr Taniwal was not a warlord or militia commander like many of his counterparts, but a sociology professor who had spent most of his life teaching in Australia.
He said he wanted to challenge the country's Kalashnikov culture, our correspondent says, but he showed himself willing to use force when necessary.
As governor of Khost province, he raised a militia to oust a warlord who refused to recognise his authority.
The latest fighting in southern Afghanistan took place in the Taleban stronghold of Panjwayi and neighbouring Zhari district, not far from Kandahar city.
Nato said insurgents suffered further casualties when a counterattack was intercepted.
Nato spokesman Maj Toby Jackson said that while the insurgents were primarily Taleban there were other elements involved.
"There are elements involved from internal, other, groups within Afghanistan, who are resisting the central government's extension," he said.
"There are also a mixture of criminality and factional fighters as part of what we describe as insurgents."
Operation Medusa, led by Canadian forces, began on 2 September and aims to drive the insurgents from their strongholds in Kandahar.
It is the biggest operation in the area since the Nato-led International Security Assistance Force (Isaf) took over southern Afghanistan from a US-led coalition at the end of July.