(Recasts with Uribe comments at Miami news conference, previous BOGOTA)

By Tom Brown

MIAMI, April 20 (Reuters) - Colombian President Alvaro Uribe, denying allegations that he supported right-wing death squads, condemned former U.S. Vice President Al Gore on Friday for pulling out of a conference where the two were scheduled to speak.

"I deplore the cancellation of the presence of Vice President Al Gore at this meeting," said Uribe, whose standing as a close U.S. ally has been undermined by the allegations.

Gore decided not to attend because of "deeply troubling" allegations that Uribe needed to address before a "very serious chapter" in Colombia's history could be brought to a close, Gore spokeswoman Kalee Kreider said in a statement.

She did not elaborate, but eight members of Uribe's congressional coalition are in jail awaiting trial for backing right-wing paramilitary groups.

More politicians, both in and out of Uribe's coalition, are being questioned as part of a widening probe into the cocaine-funded militias that have massacred thousands of Colombians in the name of fighting Marxist-led rebels.

Speaking at a news conference in Miami, where he was to have appeared at an environmental event with Gore, Uribe denied having supported the militias and challenged his critics to provide evidence of wrongdoing

"I am confident that once he (Gore) looks at Colombia closely, and he gets more information about Colombia -- and he's informed about the significant progress that Colombia has made during my administration -- he will clarify the (his) perceptions."

Visibly angry, Uribe said his government should be credited with having dismantled paramilitary groups while also making huge strides in turning back left-wing insurgents after 40 years of political bloodletting in Colombia.

"To overcome this violence is a very difficult task. We are doing our best. Maybe we have committed mistakes but we have never committed crimes," he said.

"I have never had any link with the paramilitaries," he said during the long and often rambling news conference.

"Mine is the first government to have confronted the paramilitaries and disbanded them," Uribe said.

Gore's cancellation came after U.S. Sen. Patrick Leahy, a Vermont Democrat, froze $55 million in military aid over the scandal. As chairman of the subcommittee that oversees foreign assistance, Leahy is pushing for a tougher line on Colombia, which receives billions of dollars in U.S. aid.

Uribe acknowledged that allegations about his government could hurt chances his Andean country will clinch a free trade agreement with Washington.

But he said he hoped the United States would make "the right decision regarding Colombia."

Uribe was elected in 2002 and re-elected in a 2006 landslide after cutting crime as part of his U.S.-backed crackdown on the rebels.

More than 31,000 members of right-wing paramilitary groups have handed in their guns as part of a peace deal, while Colombia's biggest rebel army, known as the FARC, continues its 43-year-old fight against the government.

Thousands are killed in the conflict every year. (Additional reporting by Hugh Bronstein, Bogota)

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