Nearly 1,900 U.S. troops traveled to strife-torn Panama Friday and thousands of Americans moved to the safety of military bases as the country's opposition party vowed to oust the Noriega regime despite annulment of fraud-tainted elections.

President Bush's decision Thursday to send the troops to help protect Americans in the Central American country drew charges from supporters of military chief and de facto ruler Gen. Manuel Noriega that the United States has "declared war on Panama."The Pentagon said the first of the 1,881 troops would arrive sometime Friday.

About 3 p.m., the first of about 6,000 military, government personnel and their dependants left their off-base homes for shelter in U.S. installations. Earlier, 142 embassy spouses and children moved onto military bases, the U.S. Southern Command said.

Expressing outrage over Noriega's alleged attempt to rig Sunday's national elections, Bush said he had ordered a brigade-size U.S. force to Panama to bolster the 10,300 troops already there.

Bush said all dependants of U.S. personnel would be moved out of Panama or to secure areas within the country, and announced he was recalling U.S. Ambassador Arthur Davis.

U.S. economic sanctions will remain in force, Bush said, and the State Department will encourage U.S. business representatives in Panama to arrange for the extended absences of their dependants.

"We are facing a war," pro-Noriega legislator Roberto Paredes told a late-night news conference called to respond to the Bush announcement. "The United States government has declared war on Panama. We are a tiny nation fighting only with our spirit."

Pedro Pereira, first deputy secretary of the pro-government Democratic Revolutionary Party, told the news conference that Noriega's forces had been "winning the election in spite of intervention and vote buying by the United States."

"We thought elections were a civilized way to solve our national problems. However, the United States began intervening, as Mr. Bush said, financing the opposition campaign with $10 million," Pereira said.

Opposition vice presidential candidate Ricardo Arias Calderon said he "strongly approved" of Bush's decision to work with Latin American and other countries to use diplomacy to solve the crisis.

Asked whether he supported the deployment of U.S. troops or possible U.S. military intervention, Arias Calderon said: "These are actions taken by the United States which have been provoked by the Noriega regime. They have not been requested by the opposition."

A Southern Command spokesman said the 6,000 Americans who began moving onto U.S. bases Thursday consisted of military personnel and their dependants, and civilian employees of the U.S. government and their dependants. He said the move should be completed by Friday afternoon.

According to Southern Command figures, there are nearly 50,000 Americans in Panama, including 14,360 military and government personnel and their 16,393 dependants. Another 19,000 Americans are in private business or are retired military personnel.

The State Department advised Americans not to travel to Panama until further notice, citing the "extremely unsettled conditions."

Two of the three opposition candidates who apparently won a resounding - but officially unrecognized - victory in Sunday's vote remained hospitalized Thursday after being beaten during a rally they were leading was broken up Wednesday afternoon. Doctors said neither was in danger.

In his announcement Thursday, Bush said the United States will meet its obligations and assert and enforce its rights under the Panama Canal treaties under which Panama will assume control of the strategic waterway in 1999.

The United States has tried since 1987 to oust Noriega through a combination of economic sanctions, covert action, propaganda campaigns and support for anti-Noriega forces inside Panama. Two federal grand juries in Florida have indicted Noriega on drug charges.