Cuban leader Fidel Castro hosted Venezuelan President Hugo Chavez and Bolivian President Evo Morales in a show of unity for the strongest critics of the United States in Latin America.

Castro, who leads the Americas' only one-party communist state, hailed his two allies, who call him "big brother."

"These new leaders have emerged and they make me the happiest man in the world," the 79-year-old leader said.

"Now, for the first time, there are three of us," he said.

Bolivia joined Cuba and Venezuela in the Bolivarian Alternative for the Americas (ALBA), an initiative promoted by Castro and Chavez in an attempt to thwart US plans for the Free Trade Area of the Americas (FTAA).

"ALBA is moving forward, and facing the aggression of the imperial projects of the free trade agreement, all we can do is attack," Chavez said. Castro added: "The best defense is to counter-attack and this is what we have done."

The trio also signed a "People's Trade Treaty" in which oil-rich Venezuela will boost crude and gas exports to Bolivia.

Morales said the treaty will help Bolivia emerge from an economic crisis.

"Only in Cuba and Venezuela can we get unconditional support," he said.

Chavez, who has become a thorn in Washington's side since his 1998 election, praised what he described as Cuba's economic achievements under the leadership of Castro, his key regional ally.

"I have been visiting this country for 12 years," he said, "and in all those years, I have seen nothing but progress, growth and victories."

Venezuela now props up Cuba's fragile centrally planned economy with its oil supplies. Cuba suffered an economic collapse after the demise of the Eastern Bloc that used to subsidize it, and it is still in dire economic straits. Cuban workers earn the equivalent of about 22 dollars a month.