Aid agencies in Afghanistan are reviewing their security arrangements after the murder of relief worker Gayle Williams.
The 34-year-old was shot dead on Monday by two gunmen on a motorcycle as she walked to work in the capital, Kabul. The Taliban claimed responsibility for the shooting saying she was killed because she was trying to spread Christianity in the conservative Islamic nation.
Ms Williams, who held dual British-South African nationality, was working for UK-based charity Serve Afghanistan, and is the latest Western civilian to be targeted.
Other charities warned the situation was becoming more dangerous and that they were reviewing their security arrangements in light of the murder.
Dominic O'Reilly, UK director of Afghanaid, said: "We will review our security, but will continue to use female staff.
"We employ low-profile security and prefer not to use armed guards, but we do review arrangements on a daily basis."
He added: "We are a much softer target than the military. Unfortunately I don't think this will be the last casualty."
Christian Aid said it had no plans to pull out of Afghanistan.
The charity has two international staff and a "small" team of local workers. A spokesman said: "Arrangements for their safety are kept under constant review.
"We work with local partners where the need is greatest, irrespective of race or religion. This was apparently accepted by Taliban when they constituted the Afghan government and we were able to work inside the country."
