Barack Obama and David Cameron have been criticised after they were caught posing for a mobile phone "selfie" at Nelson Mandela's memorial service.

The two men were sitting on either side of Danish Prime Minister Helle Thorning-Schmidt and smiled as she took the snapshot of the three leaders at the FNB Stadium in Soweto.

The image of the US President, British Prime Minister and Danish leader taking the photo quickly went viral on the internet.

It led to a backlash from Twitter users who said it was inappropriate behaviour at an event to remember the life of the anti-apartheid hero, who died last week aged 95.

Twitter user @jamesarmitage3 wrote: "What selfish morons take a 'selfie' at a memorial service? Oh yeah that's right, Barack Obama and David Cameron."

In a message directed at Mr Cameron Sarah McDermott, using the Twitter name @toxicsayonara, said: "You have precisely zero class or decorum."

Ms Thorning-Schmidt is married to former UK Labour Party leader Neil Kinnock's son Stephen, prompting questions about how Kinnock senior would feel about the image.

Writing on Twitter, Mel Huang said: "I wonder if Neil Kinnock got an ulcer seeing his daughter-in-law do a selfie with David a memorial service."