A new image of Princess Charlotte, taken by her mother Catherine, has been released to mark her ninth birthday.

The Prince and Princess of Wales shared the photo on social media, just as they did a week ago for their youngest child Prince Louis's sixth birthday.

Catherine is receiving cancer treatment and has stepped back from royal duties.

She has previously described her daughter, who is third in line to the throne, as feisty compared to George and "the one in charge".

Catherine took the photograph at Windsor in the last few days.

A similar photo of Louis shared last week was also taken by the Princess of Wales. It comes after some controversy over changes made to a Mother's Day family photograph.

Kensington Palace issued an assurance that the picture of Louis had not been edited.

A family photograph taken by the Princess of Wales and released for Mother's Day in March ended in controversy as photo agencies withdrew the picture after it emerged it had been digitally manipulated.

Kate later apologised "for any confusion", admitting she had edited the photo and saying she "occasionally" experimented.

It has been a difficult time for the Royal Family, especially Catherine and William with their young family, as the princess continues her recovery.

In January she had abdominal surgery and subsequent tests resulted in a cancer diagnosis, with treatment beginning in late February.

The King is also undergoing cancer treatment and made his first return to public engagements earlier this week. Aside from an Easter church service, King Charles has stayed away from public events since his treatment began.

Charlotte was last seen in public on Christmas Day as her family attended a church service at Sandringham.

Earlier this week, Prince William revealed his daughter's current favourite joke as he visited a school in the West Midlands.

He said: "Knock Knock". When pupils said "Who's there?" William replied: "Interrupting cow". As the group tried to say "interrupting cow who?" he said: "Mooo".