A female giant panda at Tokyo's Ueno zoo has shown signs of being pregnant, including reduced appetite and longer sleeping times, the zoo's operator said.

If 11-year-old Shin Shin does give birth, the cub will be the first giant panda born at Ueno Zoological Gardens in five years.

On Friday, the zoo put Shin Shin on public display for the first time since February, when she was housed together with male panda Ri Ri, also 11, after she appeared to be in heat.