The UK's female giant panda is keeping zoo- keepers guessing over her possible pregnancy.

If Tian Tian is to give birth, it may happen two weeks later than previously thought, experts at Edinburgh Zoo have said.

Keepers are monitoring the panda 24 hours a day and suggested on August 26 that she could produce a cub within the fortnight.

A zoo spokesman said: "In terms of Tian Tian's possible pregnancy, we're not out of the game yet, although she's keeping us on our toes."