Tian Tian, the UK's only female giant panda, is "believed'' to be pregnant and being closely monitored, according to Edinburgh Zoo.

Sources said staff at the zoo have believed the panda is pregnant since late July and that her cub could be born as early as Friday (25 August). The breeding season lasts until late September, a zoo spokesperson said.

The information was revealed in email correspondence released by the Scottish Government under the Freedom of Information Act.

​Tian Tian was moved to Scotland along with a male breeding partner, Yang Guang, in 2011. However, several attempts to get the panda pregnant failed.

She was reportedly artificially inseminated for the fifth time earlier this year after staff said it was unlikely the pair would ever mate naturally.

A spokesperson for Edinburgh Zoo said: "Giant panda breeding is a very complicated process but we believe that Tian Tian is pregnant.

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"Although a specific date was suggested, like all babies it's hard to predict precisely and the panda breeding season can last until late September.

"Tian Tian is being closely monitored by our expert team and we will be the first to share any news as soon as we can."