PANAMA CITY, JULY 3 -- Skirmishes between antigovernment protesters and riot police continued for the fourth day today as many downtown stores closed to observe an opposition strike against Panama's top military commander, Gen. Manuel Antonio Noriega.

In a sign of the prevailing uncertainty, aides to President Eric Arturo Delvalle spent the day denying a storm of rumors that he had resigned.

The national university closed until Monday, rector Abdiel Adames said, after dozens of students were injured in riots there yesterday.

The latest round of pro- and anti-Noriega disturbances erupted Tuesday, four days after the U.S. Senate passed a resolution calling for Noriega to step down. The crisis began in early June when Noriega's second-in-command, Col. Roberto Diaz Herrera, was forced out of his post and publicly accused Noriega of being involved in election fraud and assassination.

The largely middle-class opposition, organized in a coalition of business and professional groups called the National Civic Crusade, charged that Noriega had thwarted the return to electoral democracy after nearly two decades of de facto military rule. The opposition accused Noriega of amassing vast personal wealth through corrupt business dealings and of murdering Hugo Spadafora, an opponent, in 1985.

Noriega, who controls the government, fought back in recent weeks by calling the opposition "white tails," meaning that they are wealthy U.S.-backed oligarchs. He accused them of seeking to wrest power from the 20,000-troop Panamanian Defense Forces, who he said represent the poor.

The Senate resolution, echoing opposition demands, added new momentum to the protests. Leftist political forces encouraged by Noriega denounced it as intervention in Panama's affairs and attacked the U.S. Embassy Tuesday with rocks and bottles, turning the unrest into a confrontation with Washington.

Opposition protesters returned again at noon today to the main avenues of the financial district to block traffic, banging pots and waving white handkerchiefs. They were dispersed by riot police, known as Dobermans, firing buckshot. Several protesters were injured.

The big Chase Manhattan Bank branch here was closed because no employes arrived for work. Its street windows were boarded over. Yesterday two employes were detained briefly and several were beaten inside the building by police.

At dawn yesterday, pro-Noriega demonstrators smashed the ground-floor windows of the Bank of America and threw a flaming molotov cocktail into second-floor offices. No employes arrived for work there today either, bank officials said.

Anti-U.S. demonstrators also splashed red and blue paint across the front of the Citibank headquarters here. Citibank was open for business today.

Panama is a major international banking center, with about $39 billion in assets here.

The Chamber of Commerce, the main organization in the National Civic Crusade, called a general strike starting at noon to last through Sunday. The protest came in response to the looting and burning yesterday of a luxury department store belonging to Roberto Eisenmann, publisher of the opposition daily La Prensa, now in self-imposed exile in Miami.

Eisenmann is related by marriage to Delvalle, and several of Delvalle's relatives worked in Mansion Dante, the destroyed store. First Lady Mariela Diez de Delvalle yesterday condemned the attack, giving rise to reports that the president would step down. The government's National Radio denied the rumors.

At a news conference today, a broad confederation of leftist unions and grass-roots groups sought to push the government to sharpen even more its clash with the United States. The confederation called on Noriega to stop joint military exercises with U.S. troops and to expel U.S. Ambassador Arthur Davis and all other U.S. personnel who "conspired against our national interests."

An afternoon newspaper controlled by Noriega displayed a photo of the U.S. deputy chief of mission, John Maisto, captioned: "Panamanian, remember this face!" Maisto was said to be the "intellectual author" of recent opposition rioting.

A U.S. Embassy spokesperson said there have been no attacks this week on American diplomats or soldiers here, but a number of vehicles with U.S. military base stickers were stoned while parked in the streets.

Panama hosts the Southern Command, which is in charge of most U.S. troops in Latin America, and 10,000 American soldiers.