(Adds French government comment paragraphs 9-10)

By Hugh Bronstein

BOGOTA, Dec 5 (Reuters) - Families of hostages held by Colombian rebels have asked Venezuelan President Hugo Chavez to keep trying to broker a deal to free the kidnap victims despite being fired from that job by Colombia's leader two weeks ago.

A letter signed on Tuesday by 13 relatives of hostages including the mother of the French-Colombian politician Ingrid Betancourt, kidnapped in 2002, asks Chavez to keep negotiating with the Marxist guerrillas.

"You have all of our confidence and our mandate to continue meeting, talking and whatever else is needed to liberate our family members," the letter said.

Colombian President Alvaro Uribe halted Chavez's role in the negotiations on Nov. 21 after accusing him of breaking protocol by talking directly by telephone with a Colombian general and asking for information about the hostages.

Earlier, Uribe had said that only Chavez could reach a deal with the rebels thanks to their shared leftist ideology.

Chavez said he would have nothing more to do with Uribe after the conservative leader ended his role as mediator. The two countries share a 1,400-mile (2,219-km) border and are major trade partners.

Colombia on Tuesday proposed direct hostage talks with four-decade-old Revolutionary Armed Forces of Colombia, or FARC.

Uribe is drawing up a formula for advancing the negotiations with help from French President Nicolas Sarkozy, who says Betancourt's release is a high priority.

"We are going to take some initiatives very quickly," Sarkozy spokesman David Martinon said on French television.

"I can't tell you any more today," he told Betancourt's son Lorenzo Delloye, who appeared on the same program.

Pressure is mounting to find a way to free dozens of high-profile FARC captives including Betancourt, captured during her presidential campaign nearly six years ago, and three American anti-drug contractors taken in 2003.

Proof-of-life videos released by Colombia's government last week sparked an outcry over their plight. One showed Betancourt looking gaunt and despondent in her secret jungle prison.

Attempts to negotiate a deal to swap hostages for jailed rebels have been stymied over the FARC's demand that Uribe demilitarize a New York City-size area for talks. He refuses, saying that would allow the guerrillas a safe area to regroup.

The cocaine-funded FARC says it is fighting for socialism, but even left-wing Colombian politicians says the group has scant popular support. (Reporting by Hugh Bronstein; Editing by Jackie Frank)

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