By Francois Murphy

PARIS, Nov 22 (Reuters) - France urged Colombia on Thursday to reverse its decision to call off talks between Venezuelan President Hugo Chavez and Colombian Marxist guerrillas aimed at securing the release of hostages who include a French citizen.

Colombian leader Alvaro Uribe accused Chavez on Wednesday of overstepping his mandate while trying to mediate the release of hostages held by the Revolutionary Armed Forces of Colombia (FARC) and stopped the negotiations.

A day earlier, Chavez held talks in Paris with his French counterpart Nicolas Sarkozy on his efforts to secure the release of French-Colombian politician Ingrid Betancourt, who has been held by the FARC since 2002.

"We continue to think that president Chavez is the best chance of securing the release of Ingrid Betancourt and all the other hostages currently held by the FARC in Colombia," Sarkozy's spokesman David Martinon told a news conference.

The cocaine-funded guerrilla army is holding dozens of high-profile hostages in secret jungle camps, including three U.S. defence contractors, police officers, former members of Congress and provincial governors.

"We reiterate our support for the Chavez mediation, and we hope that the dialogue between president Uribe and president Chavez can restart," Martinon said.

Outspoken left-wing leader Chavez was invited in August by the conservative Uribe to broker the exchange of the hostages for guerrillas held in Colombian prisons.

The Venezuelan president spoke with Colombian armed services commander Mario Montoya on Wednesday and requested information about the hostages, Uribe said in a statement on Wednesday.

That violated an agreement that only Uribe and Chavez would hold discussions between the two neighbouring countries about hostages held by the FARC, the statement said.

Betancourt's Paris-based support committee, which includes her relatives, said in a statement earlier on Thursday it had "total confidence" in Chavez, and asked Sarkozy to intervene.

Chavez had hoped to bring Sarkozy proof that Betancourt is alive but instead he said he had received a letter from top FARC commander Manuel Marulanda pledging to prove by the end of the year that all the hostages are alive.

Betancourt has not been heard from since 2003.

"The meeting that the president had with president Chavez in Paris was certainly incomplete, dissatisfying because we did not get any proof of life," Martinon said. "But nevertheless there has been progress, very important messages were passed."

France's ambassador to Colombia will return to Bogota from Paris in the next few days to deliver a letter by Sarkozy to Uribe, Martinon said. (Additional reporting by Kerstin Gehmlich and James Mackenzie; Editing by Michael Winfrey)

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