Royal watchers are in a frenzy over a new picture of the Duke and Duchess of Cambridge with Prince George which has surfaced on Twitter.

The never-before-seen photo shows the young Prince being held by his mother, while a proud looking Prince William stands beside Kate.

The family portrait is seen in a frame which features William and Kate's royal insignias, while the photo is personally signed by them.

The photo is believed to have been taken in March by photographer Jason Bell, as part of a series of official photos.

It has been reported that the picture was presented as a gift to officials and hosts during the couple's three-week tour of Australia and New Zealand in April.

A Kensington Palace spokesman confirmed that the framed photo is an official gift that the royals often send to members of the public as a thank-you.

"I can confirm it is a photo the Duke and Duchess used as official gifts on their tour to New Zealand and Australia. It was taken by Jason Bell before the tour."

The Duke and Duchess are due to embark on a three day official tour of New York, however Prince George, who is now nearly 18 months, will be staying at home.