Mercy Corps leaves south Pakistan
The US-based aid agency Mercy Corps is pulling out of two southern Pakistani provinces for security reasons.
Nearly 50 offices in Balochistan and Sindh are to be shut.
The decision follows the kidnapping of four of the agency's local staff in February, allegedly by pro-Taliban gunmen. One has since been killed and a ransom is sought for the others.
Mercy Corps told the BBC that Pakistan's government had done little to help free the men.
Its announcement follows similar decisions by other international aid organisations, including the UN, to scale back operations in Pakistan since 2009.
"The decision has been taken following developments after the kidnapping of our team members," Dr Saeedullah Khan, head of Mercy Corps operations in Quetta, told the BBC.
He said a videotape of its employee being murdered had been sent to the organisation, with the ultimatum that the remaining three would also be killed unless a ransom of 100m rupees ($1.2m; £800,000) was handed over.
Dr Khan said the government had done little to try to get the hostages released.
"We have protested strongly and are closing down 40 offices in Balochistan, and eight in Sindh province as a protest."
Balochistan province is seen as a major safe haven for Taliban militants operating in Afghanistan. It is also the scene of an insurgency by nationalist rebels.
Security in Baluchistan has declined rapidly since 2009. Several aid workers and officials have been attacked and kidnapped.
In February 2009 a senior official of the UN agency for refugees (UNHCR), John Solecki, was kidnapped near Quetta, allegedly by Baloch nationalists.
He was released in April 2009.