Venezuela's Hugo Chavez read out Fidel Castro's remarks
Cuba's former leader Fidel Castro has accused the US of plotting to overthrow left-wing governments in Latin America.
The "friendly smile" of US President Barack Obama could not be trusted, Mr Castro said in remarks read out at a summit of leftist leaders in Havana.
His comments were echoed by Venezuelan President Hugo Chavez and other regional leaders at the meeting.
Fidel Castro's remarks suggest hopes for a thaw in US-Cuba ties may be waning, correspondents say.
As the left-wing summit drew to a close, Mr Chavez read out a letter from Fidel Castro in which he said the US was again on the offensive in Latin America.
He accused Washington of supporting right-wing governments in the region in an attempt to weaken Mr Chavez and other socialist leaders.
"The real intentions of the empire are obvious, this time hidden beneath the friendly smile and African-American face of Barack Obama," Mr Castro said.
Cuba's former leader, who was at the country's helm for nearly 50 years before handing over the presidency to his brother last year, initially welcome President Obama's election.
But in recent weeks, he has issued increasingly critical comments.
Last week, Mr Castro said that Mr Obama's acceptance of the Nobel peace prize was a "cynical act".
His criticisms were picked up by the regional leaders, who attacked Washington's handling of the political crisis in Honduras that saw President Manuel Zelaya toppled, and condemned plans by the US to use military bases in Colombia to tackle drug-trafficking.
The summit of the Bolivarian Alliance for the Peoples of America (Alba) concluded with a declaration on climate change that called on developed nations to pay for the environmental damage their economic model had caused.
Alba was founded five years ago as an alternative to US free trade policies in the region.