The World Health Organization’s ability to police the new strain of bird flu that has killed 27 people in China is being jeopardized by budget cuts, according to a top U.S. official.

“One of the things that, frankly, concerns us is the ability of WHO to respond effectively,” Dr. Thomas Frieden, director of the U.S. Centers for Disease Control and Prevention, told the Reuters Health Summit in New York on Monday.

Frieden said he planned to raise the issue with other countries at the World Health Assembly (WHA) meeting, which is being held in Geneva, where the U.N. agency has its headquarters, from May 20 to May 28.

Many scientific questions still have to be answered about the new flu strain, known as H7N9, which first caused patients to sicken in China in February having been previously unknown in humans.

So far, researchers have established it is being transmitted to people from birds – probably mostly chickens. There is no evidence of it spreading from person to person.

The WHO plays a central role in coordinating the global response to such emerging disease threats, but it is struggling in the face of budget cuts that were forced on it two years ago, partly as a result of a strong appreciation in the Swiss franc.

“They had trouble sending a team to China for H7 because they didn’t have enough money to travel,” Frieden said. “They are managing and we will help them manage – and will send staff there as needed – but the world needs them to be effective.”

Taiwan reported its first case of H7N9 on April 24 and health experts say it is critical to monitor closely the new strain’s potential to spread in neighbouring countries. Dr. Keiji Fukuda, the WHO’s assistant director-general for health security, said the organization was carrying out the work that needed to be done but the operation, involving more than 50 staff, was “very expensive”.

“We need the gas tank to be full if the car is going to move. We’ve already been working with donors in terms of response and funds for support,” he said in a telephone interview in Geneva.

There will be a side event on H7N9 during the WHA meeting on May 21 where both Dr. Margaret Chan, WHO director-general, and he will speak, along with the Chinese health minister, Fukuda added.

The U.N. health agency, which helped eliminate smallpox in the late 1970s, co-ordinated worldwide efforts to deal with the H1N1 swine flu pandemic in 2009/10.

It receives the bulk of its funding in dollars, leaving it exposed to currency fluctuations. It was forced in 2011 to cut 300 jobs in Switzerland – or one in eight – because of the strength of the Swiss franc and financial problems in some donor countries.

“They’ve had to lay off hundreds of staff in Geneva and in other parts of the world, including in areas that are quite relevant to flu response,” Frieden said.

(Additional reporting by Stephanie Nebehay in Geneva; Editing by Carol Bishopric)