A group of Olympic athletes from around the world on Sunday urged international leaders to tackle child malnutrition rates in poor countries.

Olympians including Ethiopian runner Tirunesh Dibaba and British long jumper Greg Rutherford, both gold medal winners at the London Games, were among athletes who wrote an open letter to Prime Minister David Cameron ahead of a so-called "hunger summit" at the leader's residence in No.10 Downing Street.

The letter urged Cameron to prioritize a push against malnutrition when Britain takes the presidency of the G8 next year.

Cameron later told the summit that he is "determined" that Britain help change malnutrition rates.

"While people around the planet have been enjoying and competing in these Games, there's another world where children don't have enough to eat and never get the start in life they deserve," he said. "We've a responsibility to tackle this."

Sunday's summit brought together leaders from Brazil, Kenya, Bangladesh, India and Ireland. Also invited were Ethiopian distance runner Haile Gebrselassie, Brazilian football star Pele and newly-crowned double Olympic Champion Mo Farah.

Somalia-born Farah, who has set up his own charity to raise money to help the victims of the severe drought in the Horn of Africa, said that the issue of child hunger had "touched his heart" as he urged political leaders to tackle malnutrition in the poorest parts of the world.

"I'm lucky to have set up a new life here, and growing up here, after being in Somalia as a little boy," Farah said. "But there are kids out there facing hunger and starvation and we've got to do something about it.

Gebrselassie noted that Ethiopia had won three gold medals in London, saying "just imagine what my country could have achieved if half of our children weren't suffering from malnutrition."