PARIS, June 29 (Reuters) - France, Spain and Switzerland issued a joint statement on Friday denouncing the deaths of 11 kidnapped lawmakers in Colombia and expressing their frustration at the failure to secure the release of other hostages there.

A leftist rebel force, the Revolutionary Armed Forces of Colombia (FARC) said on Thursday the 11 were killed in crossfire when an unidentified military group attacked their secret jungle hideout on June 18.

"The three countries condemn with the utmost strength those who committed this crime and demand that all light be shed on the circumstances of this massacre," said the joint statement, which was released by the French Foreign Ministry.

The Colombian government said it knew nothing of any rescue mission and accused the rebels of murdering the hostages.

The lawmakers were among about 60 high-profile hostages held by the FARC, including three U.S. defence contractors and French-Colombian politician Ingrid Betancourt, who was seized by the guerrillas during the 2002 presidential campaign.

In their rare joint statement, France, Spain and Switzerland said they had worked for years to try to resolve the crisis.

"(We) do not understand how, despite these efforts, no progress has been made. The three countries call for an end to all procrastination. They will not support any unrealistic demands," the statement said.

"These events show the urgent need for the FARC to make a strong humanitarian gesture, opening the way for a rapid, global humanitarian solution."

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