Four photo agencies have retracted a picture of the Princess of Wales over concerns it has been "manipulated".

The image, taken by Prince William and issued by Kensington Palace for Mother's Day, showed Catherine with their three children.

But Associated Press was the first to pull the image as it "did not meet" the agency's photo standards. The agency noted an "inconsistency in alignment of Princess Charlotte's left hand".

Kensington Palace declined to comment.

The photo shows the princess sitting down, surrounded by Princess Charlotte, Prince Louis and Prince George, the latter wrapping his arms around her.

It was the first official photo of the Princess of Wales since her abdominal surgery two months ago. Since then she has stayed out of the public eye.

The image was posted on the Prince and Princess of Wales's social media accounts with a message from Catherine which said: "Thank you for your kind wishes and continued support over the last two months.

"Wishing everyone a Happy Mother's Day."

It has become a regular routine for the royal couple to release their own photos of special family occasions. More often than not, the photos are taken by Catherine and are issued to the media with instructions on how they can be used.

The Mother's Day image was included on the front pages of several national newspapers and websites, including BBC News, and used on TV news bulletins - again including the BBC.

But, late on Sunday, the Associated Press, one of many international agencies that distributed the photo, issued a "kill notification" - an industry term used to make a retraction.

It said: "At closer inspection it appears that the source has manipulated the image. No replacement photo will be sent."

A second news agency, Reuters, said it too had withdrawn the image "following a post-publication review". This was followed by a third agency, AFP, which also issued a "mandatory kill notice".

Getty Images became the fourth organisation to retract the photograph.

PA Media, the UK's biggest news agency - through which the Royal Family regularly releases its official information, including to the BBC - said it had not killed the picture on its service.

But, a spokesman said the agency was seeking urgent clarification from Kensington Palace over the concerns raised about manipulation.

Most news organisations follow their own strict guidelines on the use of manipulated photographs, only using them when accompanied by an explanation that the image has been changed from the original.

News agencies, such as AP, therefore make a commitment to their clients that their photos are accurate and not digitally manipulated.

AP's rules only allow "minor adjustments" in certain circumstances including the removal of dust on camera sensors.

Catherine, 42, spent 13 nights at the London Clinic, near Regent's Park in central London, following the surgery.

Prince William visited his wife during her stay and she was visited by the King before he had his own treatment there.

The Palace has shared few details about her condition, which has garnered significant social media speculation, but has said it is not cancer-related.

The team supporting the princess as she recovers is small and limited to those closest to her.

At the time of her stay, the Palace said the princess wanted her personal medical information to remain private, adding that she wanted to "maintain as much normality for her children as possible".

The Palace said it would only provide updates on her recovery when there was significant new information to share.

It was thought on Sunday morning the photo would quell some of the more extreme theories around the princess's absence from the public stage. But within hours social media was abuzz with zoomed-in images of Princess Charlotte's left cuff and Prince Louis' fingers.