A scientist displays Aedes aegypti mosquitoes inside the International Atomic Energy Agency's (IAEA) insect pest control laboratory in Seibersdorf, Austria, February 10, 2016. REUTERS/Leonhard Foeger TPX IMAGES OF THE DAY

LONDON (Reuters) - Porton Down, the British government center famous for its Cold War germ warfare research, said on Wednesday it was working hard to keep up with demand for Zika virus samples as scientists around the world scramble for them.

The National Collection of Pathogenic Viruses (NCPV) is one of a handful of centers worldwide that make viruses available to authorized scientists - and not all of them have managed to satisfy their customers.

The non-profit ATCC in Virginia, for example, says on its website that Zika virus is currently on backorder pending production of a new lot, following recent high demand.

Until recently Zika was a virological oddity of no obvious public health concern and little scientific interest, but its suspected connection to birth defects in Brazil has sparked unprecedented demand from research groups.

The NCPV said it had been monitoring the developing epidemic in Brazil during 2015 to ensure stocks remained available and it was now responding to numerous supply enquiries every day.

“We are continuing to monitor the situation and will restock as necessary, in response to this sudden spike in research demand,” a spokeswoman said on Wednesday.

The center supplies frozen cultures of Zika and RNA extracted from the virus to research laboratories across the world, provided they meet stringent biosafety containment standards.

An ampoule of Zika virus costs 334.75 pounds ($484.72), while virus RNA is priced at 384.75, according to the NCPV website.

($1 = 0.6906 pounds)