Islamabad (CNN) -- In a three-minute video posted to the internet, Warren Weinstein begs the U.S. President to meet the demands of his Pakistani kidnappers in return for his life.
Weinstein is one of a growing number of aid workers seized at gunpoint by violent extremists and criminal gangs in Pakistan who are demanding ransoms in exchange for their captives' lives.
"I am very concerned about the future and not too optimistic about the situation," said a British aid worker based in Islamabad who asked not be named because he wasn't authorized to talk.
According to the Pakistan Humanitarian Forum (PHF), a coalition of humanitarian organizations, 19 aid workers have been murdered in Pakistan since 2009. At least 23 have been kidnapped.
In the first two months of this year alone, five aid workers have been abducted and another three killed in separate instances, according to PHF.
They included Khalil Rasjed Dale, a 60-year-old worker for the International Committee of the Red Cross (ICRC), whose battered body was found dumped in the southwestern city of Quetta in April, four months after he was kidnapped at gunpoint on his way home from work.
The ICRC declined to comment on reports that Dale was beheaded, saying only that his murder was "brutal." A note found on Dale's body said he had been killed because ransom demands were not met.
The PHF warns the increase in murders and kidnappings will further disrupt the ability of aid groups to provide support for millions of Pakistanis in need of healthcare and disaster-relief.
The ICRC has already decided to suspend operations across much of Pakistan. The Red Cross has placed 900 national staff members on paid leave and flown 80 international staffers to Islamabad, said spokesman Christian Cardon.
Jacques de Maio, the head of Red Cross operations for South Asia, said the aid agency was compelled to "completely reassess the balance between the humanitarian impact of our activities and the risks faced by our staff."
Some aid workers in Islamabad said the ICRC's decision to halt much of its work was a drastic measure that places millions of vulnerable Pakistanis in jeopardy. However, the aid worker who spoke to CNN said the decision if and when to pull out was best left to each aid organization.
"Only if and when such an appalling thing happens can you know how to react. I can't say what I would do," he said.
Despite the fresh concern over safety and the risks of working in regions beset by militants and criminals, scores of national and international aid workers, with thousands of staffers, continue to operate in Pakistan.
"We work in places of conflict, where things are volatile and where anything can happen," said the British aid worker. "There are obviously risks involved. We are all aware of those risks. That said, we try to mitigate those risks."