Experts have warned that the disease has the potential to mutate and transmit from human to human, and China withholding samples of the virus hampers the development of vaccines.
UK sources confirmed that Britain had also requested a sample for research, but had not received one, with “safety considerations” cited.
The H7N9 virus is capable of transmitting from birds to humans, and there have been hundreds of cases reported, mainly in China. The virus is highly deadly when established in humans.
While it cannot yet spread from human to human, there are fears that if it mutates it could cause a global pandemic.
Media reports about the matter have cited a souring trading relationship between the states and the US, as well as potential commercial reasons, for withholding samples.
Prof Ian Jones, of the University of Reading, told the Telegraph: “If the virus is going to jump you want to be ahead of the game with a vaccine,” said Professor Ian Jones, an expert in virology at the University of Reading. “If the virus were to jump it would become a pandemic strain.”