A refugee from Sudan's civil war has won his battle to compete in the Olympic marathon as an independent runner without a country.

US-based Guor Marial had turned down the chance to run for Sudan, could not represent America because he is not a full citizen and was unable to wear the colours of his first choice, South Sudan, because it is not sending a team to London.

But the 28-year-old's late plea to enter as a stateless athlete under the Olympic flag has now been granted by the International Olympic Committee (IOC). Marial was preparing for a training session over the weekend when he got the career-changing call.

"I was getting ready to go for a run," Marial told the Associated Press from his home in Flagstaff, Arizona. "Wow. This is so exciting. It's hard to describe. I'm speechless."

Marial lost 28 family members to violence or disease during the civil war that left Sudan devastated and eventually led to the south breaking away last year. He felt that representing Sudan would betray their memory, but competing in the Games this way will honour them.

He told Reuters: "For me, it means a lot to glorify the people who died for their freedom and people who lost their lives, including 28 members of my family and relatives. Their spirit is what allows me to get up every single day, put on my shoes and train to honour them."

He has bleak childhood memories of the conflict. One night, soldiers raided his home, smashing his jaw with a rifle and knocking him unconscious. At the age of eight, he was forced to escape a labour camp after being kidnapped by gunmen. He hid in a cave until dawn, then followed the path of the sun.

"I used to hate running," he told AP. "I was running back home to save my life."

Marial lived in Egypt before reaching the US 12 years ago. He showed promise as a cross-country runner at Iowa State University. Last October he beat the Olympic marathon qualification time and in June improved his personal best to two hours, 12 minutes and 55 seconds.

South Sudan has been torn by economic collapse, tribal violence and a brewing conflict with its northern neighbour since becoming independent little more than a year ago. Establishing an Olympic body is hardly a priority and so it won't be taking part in the Games.

But Marial, whose kit is expected to be Olympic-branded, is looking forward to running for his country in an unofficial capacity on 12 August, the climax of the Games. "To have someone at the Olympics after one year of independence and [knowing] the whole world will see it, that's amazing," he told Reuters.

Marial said he would ask his father, who still lives in South Sudan, to travel to the nearest city to watch him on TV.

In an interview with AP, he added: "South Sudan has finally got a spot in the world community. Even though I will not carry their flag in this Olympic Games, the country itself is there. The dream has come true. The hope of South Sudan is alive."

Refugees International, an advocacy organisation that had lobbied the IOC to allow Marial to participate, welcomed the decision. Michel Gabaudan, its president, said: "It's a great message to Guor Marial and also South Sudan. First he was offered the chance to run for Sudan which he very politely but very firmly turned down for understandable reasons.

"Everyone will know he is from South Sudan and it is great for a young country with all the problems they have. The country needs a bit of good news and we are thrilled."

Three athletes from the former Netherlands Antilles will also compete under the Olympic flag. Should any of them win an event, it is thought the Olympic anthem composed by Spiro Samara will be played in lieu of a national anthem.