(Reuters) - Guor Marial will run under the Olympic flag when the starting pistol sounds for the men's marathon on August 12 but deep inside, the 28-year-old will be brimming with pride at becoming the first athlete to represent South Sudan.

Marial moved to the United States 12 years ago and given that South Sudan only declared independence in 2011 after decades of civil war and has yet to establish a National Olympic Committee, it cannot send a team to the London Games.

The runner does not hold U.S. citizenship and refused an offer to represent Sudan, but on Saturday the International Olympic Committee (IOC) announced that Marial could line up for the marathon as an independent participant.

"It's very emotional and it raises high hopes for the young kids especially," Marial told Reuters in Arizona shortly after receiving the news.

"It means a lot... and 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, you know combined -- extended family.

"Their spirit is what allows me to get up every single day and put on my shoes and train to honor them."

Marial ran faster than the Olympic qualification time last October and improved his personal best in San Diego, California in June, finishing in two hours, 12 minutes and 55 seconds.

His times suggest he will not be just making up the numbers but while the likelihood of winning a medal remains a distant dream, Marial is delighted to have been given an opportunity to put his country on the global stage.

"To have someone at the Olympics after one year of independence and everyone will see that and even the whole world will see it. That's amazing," he added.

"I just want to have fun, put the jersey on, the Olympic jersey or whatever they give me to wear and just enjoy it. In the race you don't want to think about it, because anything can happen. For me, I'm going to the Olympics with an open mind."

Three athletes from the former Netherlands Antilles will also compete under the Olympic flag.

(Writing by John O'Brien in Singapore; Editing by Amlan Chakraborty)