By Jeff Franks

HAVANA (Reuters) - Both the United States and Cuba would benefit if Washington would lift its longstanding trade embargo against the island, but U.S. President Barack Obama has toughened the sanctions since taking office in 2009, a top Cuban official said on Thursday.

The embargo, fully in place since 1962, has done $108 billion in damage to the Cuba economy, but also has violated the constitutional rights of Americans and made a market of 11 million people off limits to U.S. companies, Foreign Minister Bruno Rodriguez told reporters.

"The blockade is, without doubt, the principal cause of the economic problems of our country and the essential obstacle for (our) development," he said, using Cuba's term for the embargo.

"The blockade provokes suffering, shortages, difficulties that reach each Cuban family, each Cuban child," Rodriguez said.

He spoke at a press conference that Cuba stages each year ahead of what has become an annual vote in the United Nations on a resolution condemning the embargo. The vote is expected to take place next month.

Last year, 186 countries voted for the resolution, while only the United States and Israel supported the embargo, Rodriguez said.

Lifting the embargo would improve the image of the United States around the world, he said, adding that it would also end what he called a "massive, flagrant and systematic violation of human rights."

That violation includes restrictions on U.S. travel to the island that require most Americans to get U.S. government permission to visit and a ban on most U.S. companies doing business in Cuba, he said.

"The prohibition of travel for Americans is an atrocity from the constitutional point of view," Rodriguez said.

Cuba has its own limits on travel that make it difficult for most of its citizens to leave the country for any destination.

Rodriguez said the elimination of the embargo would provide a much-needed tonic for the sluggish U.S. economy.

"In a moment of economic crisis, lifting the blockade would contribute to the United States a totally new market of 11 million people. It would generate employment and end the situation in which American companies cannot compete in Cuba," he said.

Obama, who said early in his presidency that he wanted to recast long-hostile U.S.-Cuba relations, has been a disappointment to the Cuban government, which expected him to do more to dismantle the embargo.

He has lifted some restrictions on travel and all on the sending of remittances to the island, but Rodriguez said he has broadened the embargo and its enforcement in other areas.

Fines against U.S. and foreign companies and individuals who have violated the embargo have climbed from $89 million in 2011 to $622 million so far this year, he said.

U.S.-Cuba relations thawed briefly under Obama, but progress came to a halt when Cuba arrested U.S. contractor Alan Gross in Havana in December 2009.

Gross was subsequently sentenced to 15 years in prison for setting up Internet networks in Cuba under a controversial U.S. program that Cuba views as subversive.

Rodriguez dodged questions about how U.S. policy toward Cuba might change if Obama is re-elected in November or if Republican candidate Mitt Romney wins the presidency, but said whoever is in office will have a chance to make history.

"Any American president would have the opportunity to make a historic change," he said. "He would go into history as the man who rectified a policy that has failed."

(Reporting by Jeff Franks; Editing by Tom Brown and Jackie Frank)