TIAN Tian the panda is still behaving as though she is pregnant, experts said as their anxious wait continued for the arrival of a cub.

Edinburgh Zoo said they were still within the time-frame for a possible birth but stressed she was "definitely not a textbook panda".

Panda breeding is not an exact science and it remains difficult to tell if a female panda is expecting a cub, the zoo said in a statement.

Tian Tian has been ­keeping the public and her keepers guessing over her possible pregnancy since she was artificially inseminated in April.

In August, Edinburgh Zoo said she was showing encouraging signs of pregnancy. Tian Tian was later placed on 24-hour surveillance, with early expectations she could give birth in late August or September.

In early September, the zoo cautioned that any birth could happen two weeks later than previously thought.

Now it remains the case that no one can say for sure whether the panda is pregnant, or, if she is, when she might give birth.

Edinburgh Zoo said it was still possible Tian Tian was expecting and they would continue to prepare for a new arrival.

Gestation periods in pandas are recorded as ranging from between three to 11 months.

A spokeswoman for the Royal Zoological Society of Scotland, which runs the zoo, said: "Panda breeding is not a precise science and, combined with this, each animal has their own ­individual biology and Tian Tian is definitely not a textbook panda."

"While Tian Tian ­continues to behave like she's pregnant and while her hormones, behaviour and physical changes suggest the same, we will continue to manage her accordingly; as soon as we know otherwise we will, of course, announce this. To put it into context, there are no experts around the world who can say definitively how long a giant panda pregnancy is.

"A large number of cutting-edge scientific tests are still in their infancy. In fact, Tian Tian is only the third panda many of these have been trialled on."