David Cameron "muscled in" on a controversial world leaders' "selfie" photograph taken at a memorial service for former South African president and anti-apartheid hero Nelson Mandela, the husband of one of those involved said.

Stephen Kinnock, son of former Labour leader Neil Kinnock who is married to Danish premier Helle Thorning-Schmidt, rejected the Prime Minister's claim that he had been invited to join her and US president Barack Obama in the snap.

The would-be MP, who is poised to enter the Commons next year after being selected for a safe Labour seat, also criticised his party's "hectoring" approach to business.

And he suggested that party leader Ed Miliband ignored the advice of aides when he publicly ate a bacon sandwich - and ended up being ridiculed on social media.

Challenged in the Commons at the time amid widespread criticism of the decision to pose for the photo, Mr Cameron told MPs: "When a member of the Kinnock family asked me for a photograph, I thought it was only polite to say yes."

But Mr Kinnock told the Huffington Post website: "For me, the most striking thing about the selfie was our Prime Minister muscling in on the left.

"She was sitting and ­chatting with Obama, then the selfie idea somehow emerged, and then suddenly Cameron appeared in shot and managed to muscle himself in on the picture."

He said he was sure that the picture, as yet unpublished, would be released by his wife "later down the track".

Mr Cameron has said Ms Thorning-Schmidt assured him it would remain unseen "until we have all retired".

Mr Kinnock, whose sister Rachel is an aide to Mr Miliband, played down suggestions of dissent within the Labour leader's inner circle.

"If it's such a desperately unhappy place, why has nobody left? People are absolutely passionate about getting Ed into No 10 and they will do whatever they can. You take the rough with the smooth," he said.