It is hoped that the drug will boost their famously feeble attempts to mate.

Who would want to mate in front of an audience?

Sally Nicholson, WWF, on captive pandas aversion to sex

Poaching and loss of habitat have reduced the worldwide giant panda population to just 1,000 and many warnings of extinction have been made.

Most efforts to breed the animals in captivity have failed, leading to a recent project to clone panda embryos with the intention of artificially implanting them.

Coy boys

The problem with many captive pandas is that they are curiously coy about amorous advances from the opposite sex.

Whether Viagra, which helps stimulate an erection, will help is not known, but the newspaper said: "The male panda can only mate for at most 30 seconds at a time and hence the chances of getting the female pregnant are very low.

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"With Viagra, the male could last for up to 20 minutes."

Mating myth

Sally Nicholson, Head of International Policy at the World Wildlife Fund for Nature, told BBC News Online: "There is a myth about pandas being reluctant to mate. In the wild, they can certainly do it, but in captivity they do have a problem which no-one has yet cracked.

"I say good luck to the researchers testing the Viagra, as long as they are very careful to avoid any damaging side effects."

But Ms Nicholson, who is in frequent contact with WWF's panda programme in China, added that WWF's primary concern was the protection of the panda's habitat: "Pandas can survive in the next century if their habitats are protected - the recent logging ban by the Chinese government is very good news."

After all, she pointed out, even if captive breeding was successful, "pandas cannot be reintroduced to habitat which is not there".

Chinese medicine

Zhang Hemin, director of a panda centre in the central province of Sichuan, told the the Wen Hui Daily he was unsure if Viagra would help.

"We tried to give them Chinese medicine in the mid-1990s," he said.

"As a result, the sex drive of the pandas did improve but they also became hot-tempered and attacked the females. That obviously wasn't so good and we had to end the experiment."

Mr Zhang said: "The real problem is that many pandas do not know how to mate."