Gayle Williams was volunteering in Afghanistan when she was killed
A woman working for a UK-registered charity has been shot dead near Kabul University in the Afghan capital.
Gayle Williams, 34, was a UK and South African national. She was killed by two men on a motorbike, witnesses told the BBC.
The Taleban are reported to have said they killed her because she was working for a Christian organisation called Serve Afghanistan.
In August the Taleban killed three foreign women near Kabul.
Ms Williams was killed while walking to work, police said.
An eyewitness told the BBC that two men on a motorbike drew alongside her. One man then got off the motorbike and shot her six times at close range before jumping back on the bike and escaping.
Mike Lyth paid tribute to Ms Williams
Children on the street going to school also saw the incident.
"Some bullets hit her body and some hit her leg and when police got there she was dead," interior ministry spokesman Zemarai Bashary told the AFP news agency.
The BBC's Martin Patience in Kabul says this is not the first time that a foreigner has been killed in the Afghan capital by armed men.
But the incident will raise further concerns about the security situation in Afghanistan, our correspondent says.
In the past week, there have been three assassinations in the southern city of Kandahar, all carried out by men on motorbikes.
Serve Afghanistan is a UK registered charity whose overseas staff are volunteers. It focuses on education and training for people with disabilities.
The charity's chairman, Mike Lyth, said the staff and volunteers were in shock over the killing.
He said: "She had been there for about two-and-a-half-years and was managing a community development project focused on disabled people.
"We are deeply saddened about what has happened. She was absolutely lovely and was full of life. A sportswoman and mountaineer - she just loved that sort of thing.
Police at the scene of the shooting
"The thought of Afghanistan must have seemed an adventure for her."
Ms Williams was brought up in South Africa but spent several years living in the UK.
She qualified as a fitness instructor and spent some time in London looking after children with severe special needs before deciding to volunteer in Afghanistan.
She was based in Kandahar but returned to Kabul when the situation there became too dangerous.
Taleban spokesman Zabiullah Mujahid told AFP that they killed Ms Williams "because she was working for an organisation which was preaching Christianity in Afghanistan".
Mr Lyth believed more attacks were imminent and said: "It is happening increasingly often in countries like Afghanistan. It is a policy of the Taleban to destabilise and knock the government by knocking out all of the aid and NGOs working there."
He said Ms Williams's fellow volunteers needed to discuss their next course of action.
Colleague Rina van der Ende said the news was still difficult to comprehend.
She said: "It still feels unreal that Gayle is not here. She was a very cheerful lady who was always eager to help and we were happy to have her at meetings.
Gayle Williams's coffin outside a Kabul hospital
"She was walking to the office. She had to pick up some papers because she had to give training to the Afghan staff about how to work with people with disabilities."
Her Kabul-based colleagues also released a joint statement, calling Ms Williams an "inspiring" person who "put others before herself".
The secretary of state for international development, Douglas Alexander, called the killing a "callous and cowardly act".
He said: "To present her killing as a religious act is as despicable as it is absurd - it was cold blooded murder."
Ms Williams leaves behind her mother in the UK and a sister in South Africa.
This year 29 aid workers have been killed in Afghanistan; five of whom were international staff.
In August another aid group, the International Rescue Committee, suspended operations after three of its foreign female staff - a British-Canadian, a Canadian and a Trinidadian-American - were shot with their Afghan driver close to Kabul.
The Taleban claimed responsibility for that attack, saying the women were foreign spies.
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