PARIS, June 5 (Reuters) - French President Nicolas Sarkozy will lobby other world leaders at this week's Group of Eight summit in Germany to push for the release of French-Colombian hostage Ingrid Betancourt, a spokesman said on Tuesday.

Betancourt is one of the most high-profile kidnap victims in Colombia, where she has been held since February 2002 by the largest rebel group, the Revolutionary Armed Forces of Colombia, or FARC.

Sarkozy has made pushing for her release a foreign policy priority, and Colombian President Alvaro Uribe said it was at Sarkozy's request that he freed a senior FARC member on Monday in a bid to broker a deal with the rebels.

"He will discuss it with the G8, he will discuss it with the five big developing (countries)," Sarkozy's spokesman David Martinon told reporters after the president met relatives of Betancourt following the overnight release of the FARC member.

"He wants to make the G8 aware of this problem, which is extremely important to us," Martinon added.

Rodrigo Granda, known as FARC's "foreign minister", was released so that he could act as a "facilitator" between Bogota and the rebels, raising hopes of an agreement to free prisoners held for years in Latin America's oldest guerrilla war.

Besides Betancourt, who was kidnapped while campaigning for the presidency along with her assistant Clara Rojas, FARC's prisoners include three U.S. defense department contract workers who were snatched in 2003.

Martinon said winning the backing of G8 leaders would be useful but would not secure a breakthrough.

"The solution will not come from the G8 but the G8's commitment can be an additional weapon in this process, which is difficult and complicated," he said.

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