Obama, Cameron, Schmidt take selfie at Mandela memorial

It is being described as one of the highest-powered "selfies" ever snapped.

US President Barack Obama, UK Prime Minister David Cameron, and Denmark's PM Helle Thorning-Schmidt took an impromptu photograph of themselves at the memorial service for the late South African President Nelson Mandela.

The snap joins what one commentator has suggested is the "interesting social phenomenon" of people taking "selfies" in serious places.