"It is unfortunate that Chavez has retained his grip on power in Venezuela," said a statement from Ileana Ros-Lehtinen, the influential chairwoman of the House foreign affairs committee.

"Chavez has denied access to international election monitors, employed last minute ballot changes, controlled the judicial system, harassed independent journalists, and consolidated his power to manipulate the vote in his favor," she said.

Mentored by Cuba's Fidel Castro, Chavez has become the leading voice of Latin America's left, railing against the US "empire" while befriending Iran and Syria.

He was re-elected to another six-year term Sunday after seeing off a stiff challenge from youthful opposition leader Henrique Capriles, who conceded victory, saying: "I accept and respect the decision of the people."

A highly polarizing figure who survived a coup in 2002 and became popular with the long-neglected poor for using the country's vast oil wealth to fund health and education programs, Chavez is now accused of widespread corruption and cronyism.

"Chavez must not be allowed to continue to export his hate and despotism abroad like his fellow dictators in Iran and Cuba through the oppression of the press and violation of human rights," said Ros-Lehtinen.

"The United States and responsible nations must remain steadfast in our defense of democracy and freedom and not bow to Chavez's tyranny."