PANAMA CITY, JULY 4 -- Protesters dressed in white and waving white handkerchiefs today held the largest demonstration against the government controlled by top military commander Gen. Manuel Antonio Noriega since he took up his post four years ago.

About 6,000 mainly middle-class women marched peacefully for three hours through downtown Panama City.

They were followed by a broad line of cars at least a mile long, blocking traffic and honking horns in a deafening din.

In contrast to recent days, no riot police, known here as Dobermans, tried to break up the march. The mood was cheerful, and many demonstrators came out with small children in their cars to demand that Noriega step down.

However, a three-day business strike called Friday by the National Civic Crusade, the main opposition coalition, was only partially successful this morning, as some small shops left their doors open enough for shoppers to enter.

The U.S. military in Panama held a subdued Fourth of July parade at Fort Clayton, on the outskirts of the capital. The only marchers allowed to wear uniforms were members of an ROTC unit from the American high school here.

The U.S. military went civilian as a precaution because of the tense confrontation this week between Washington and Noriega.

Even Gen. Fred Woerner, top officer of the U.S. Southern Command, sported a Panamanian-style white cotton shirt to review the parade.

Last year, hundreds of combat-uniformed Panamanian Defense Forces troops paraded down the blacktop with American servicemen.

But Noriega canceled his appearance this year and didn't send any soldiers.

Last Tuesday, the U.S. Embassy was hit with rocks and bottles in a demonstration that was attended by high-ranking Panamanian officials and political supporters of Noriega. The demonstrators were protesting a U.S. Senate resolution last week calling on the Panamanian government to oust Noriega and investigate allegations of his involvement in assassination and election fraud.

Today, after a window-rattling 50-gun salute at the Fourth of July festivities, U.S. Ambassador Arthur Davis told reporters that the situation in Panama is "tenuous," but added that he expects "productive measures" and "positive changes" in the coming week. He declined to be more specific.

President Eric Arturo Delvalle is scheduled to make a speech Sunday on national radio and television and is expected to suggest talks between the government and opposition parties, The Associated Press reported.

The government has made several attempts to appease the opposition. Late Friday, under the auspices of Archbishop Marcos Gregorio McGrath, three government officials close to Delvalle met privately with several opposition businessmen to explore the possibility of a dialogue, according to a politician familiar with the encounter.

But the discussion, led by Commerce Minister Jose Bernardo Cardenas, collapsed because the opposition insisted that Noriega resign, the source said.

Also Friday, Ramon Sieiro, Norieg'a brother-in-law and head of a progovernment political party, issued a public call for dialogue.

But Ricardo Arias Calderon, leader of the opposition Christian Democratic Party, today rejected that overture as another attempt to soften the demand for Noriega to leave.