A major UK news agency, PA, has become the fifth picture service to withdraw a photo of the Princess of Wales and her children over concerns about the image.

Four international photo agencies had already retracted the picture because of concerns it has been "manipulated".

The photo, taken by Prince William for Mother's Day, was the first of Catherine to be released by Kensington Palace since her surgery in January.

Kensington Palace declined to comment.

Earlier, Getty Images, AFP, Reuters and Associated Press pulled the photo - noting an "inconsistency in alignment of Princess Charlotte's left hand".

PA news agency said the image, originally posted by Kensington Palace on their social media, was provided "in good faith".

But in a statement it added: "We became aware of concerns about the image and we carried a report about it last night, and made clear that we were seeking urgent clarification about the image from Kensington Palace.

"In the absence of that clarification, we are killing the image from our picture service."

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.

But, before Prince William's image of his family was posted online, it would have gone through the social media team at Kensington Palace who manage the online accounts of the Prince and Princess of Wales.

It may well have been that some editing was done on the original photo which has now resulted in the discrepancies in its appearance.

The implication here is not that the entire photo is a fake or that the Princess of Wales is more unwell than she appears in the image. That seems unlikely and would be a very high-risk strategy from the Kensington Palace team.

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.

In order to use the new photo as quickly as possible, the BBC took the one used by Kensington Palace on their social media accounts.

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.