Foreign Minister David Choquehuanca said U.S. citizens would now fall under Bolivia's most highly regulated migratory category. A 30-day tourist visa will cost $134, an amount similar to fees paid by Bolivian citizens applying to enter the United States.

U.S. tourists now need only fill out a small form upon entering Bolivia, which grants them 30 days' stay with the chance to apply for up to 90 days.

The new category requires proof of "economic solvency," proof of hotel reservations for the entire planned visit or a notarized invitation from a Bolivian citizen, a yellow fever vaccine, and a small passport photo taken against a "red background," though Choquehuanca hinted the process might be simplified.

"We are working to not hurt the flow of foreign tourists," Choquehuanca said. U.S. visitors "will be able to obtain a visa at the point of entry, either on the border or right there in the airport."

However, the Bolivian state news agency later said the visas would be given at points of entry only after "the requirements established by law were previously completed," presumably through one Bolivia's eight U.S. consulates.

The Bolivian Tourism Chamber says one in five tourists visiting Bolivia is from the United States, and more than 70,000 Americans visited in 2005, the last year for which estimates were available. Americans spend about $40 million a year in South America's poorest country.

Morales has called Bolivia's new policy "a matter of reciprocity."

The U.S. government requires Bolivians to obtain visas to enter the United States, charging $100 for each visa plus a $14 fee per family to begin the application process.

U.S. ties to Bolivia have been tense since Morales took office last year. The United States is wary of Morales' friendship with Cuba's Fidel Castro and Hugo Chavez of Venezuela, while Morales has accused the United States of supporting the opposition.