PANAMA CITY, AUG. 6 -- Tens of thousands of Panamanians held an easy-going demonstration today to call for the ouster of military strongman Gen. Manuel Antonio Noriega after the government lifted a ban on the protest.

The mainly middle-class opposition got its first chance since a political crisis began two months ago to show how big a crowd it could muster. At mid-afternoon, about 10 blocks of a main boulevard in the financial district were clogged with strolling demonstrators clad in white, the color of the opposition, in what looked more like a promenade than a militant action.

The demonstration was first called for July 10, but riot police blocked it with shotguns and tear gas in a day-long melee.

Today's turnout was comparable in size to a rally that pro-Noriega forces held last Friday to honor the late nationalist leader, general Omar Torrijos. However, many at that event were public employes and government party stalwarts bused in from the provinces.

The peaceful events seem to indicate that the government, which Noriega has run behind the scenes since 1983, is stepping back from recent harsh measures. Last week Noriega's Defense Forces closed three daily newspapers and two weekly magazines and expelled Tom Brown, a correspondent for the Reuters news agency.

On Monday, troops arrested Roberto Diaz Herrera, a retired colonel and Noriega's former deputy. His allegations in early June about military corruption and about Noriega's involvement in murder and election fraud ignited the current wave of popular protests.

Yesterday, Panama City Mayor Jilma Noriega de Jurado, a relative of the general, prohibited the march planned for today and called on police to repress it. But this morning she lifted her order, at the request, she said, of President Eric Arturo Delvalle.

The president told her in a phone call last night that "he had a commitment with the opposition to allow the demonstration," the mayor said.

A presidential ban on all public demonstrations had been in effect since July 5. But leaders of the government's Democratic Revolutionary Party said the presidential decree was left with little effect after their party turned out about 50,000 of its supporters last Friday.

"If we went out, let them go out and show us what they can do," said one top government party leader who did not wish to be named.

The short notice gave opposition organizers little time to communicate with their followers. The rally that convened in front of the banking district's El Carmen church was free form, with no podium or speakers.

Protesters waved white handkerchiefs, the opposition symbol, and shouted "Mango! Mango!", a combination of Noriega's initials (M.A.N.) and the English word "go."

The leaders of the National Civic Crusade, a coalition of 112 business and professional groups that called today's action, could not attend because they remain in hiding after the authorities issued warrants for their arrest yesterday.

At least six men, including Chamber of Commerce President Aurelio Barria Jr. and Eduardo Vallarino, president of National Private Enterprise Council, are wanted for conspiring to overthrow the government, Attorney General Carlos Villalaz said yesterday.

The warrants were issued after police raided the Chamber of Commerce and the offices of a business executives' association Tuesday. Police claimed documents they captured there revealed that crusade leaders had plotted with the United States and exorted their followers to violence.

One of the documents cited was a crusade pamphlet urging demonstrators to carry plastic bags full of engine oil to throw on the ground in front of policemen to make them slip and fall.

None of the opposition leaders was arrested today.

The opposition has called the attorney general's accusations a "huge lie" and charged that the orders for the arrests of the six men were part of a campaign aimed at silencing critics and scaring people away from today's rally.

Meanwhile, Noriega and Delvalle refused to meet with a delegation from the Inter-American Press Association conducting an inquiry into press censorship, delegation leader Alejandro Miro Quesada said.

In another development, government party President Romulo Escobar Bethancourt, in an interview, said he will press for new financial measures from the goverment that run counter to a World Bank austerity program Panama undertook to cope with its $3.8 billion foreign debt.

Bethancourt said the party will demand price controls on basic foods and a new contract with Panama's only refinery to lower the price of fuels. The refinery is privately owned by Panamanian and American companies. Bethancourt said the party is not demanding that the refinery be nationalized.