PANAMA CITY, JULY 12 -- Dozens of Panamanians remained in jail today after being detained in disturbances Friday, and several opposition leaders were in hiding.

By late yesterday the government had freed all 10 Americans arrested in roundups Friday by police who stopped opposition protesters from holding a major demonstration, a U.S. Embassy spokeswoman said.

Yesterday, authorities at Modelo prison released 133 of about 300 people detained in the turmoil. But 145 prisoners were held for further investigation, including 15 singled out as "white tails," a slang term for affluent Panamanians, according to a progovernment newspaper account.

During a five-week-old crisis thousands of Panamanians have been detained, but until now they were generally freed after a few hours.

The middle-class opposition is calling for the top military commander, Gen. Manuel Antonio Noriega, to step down because he has been accused of murder and corruption. Noriega responded last week that the protests were the work of "only 5,000" aristocratic Panamanians who did not represent a majority sentiment.

Noriega is seeking to postpone his retirement to complete 30 years of service instead of the regulation 25, his spokesman said Friday. Technically Noriega was due to retire in May.

One U.S. airman and three other Americans with ties to the U.S. Southern Command and the Panama Canal Commission here were among those detained, a U.S. military spokesman said.

The four, pictured yesterday in a Noriega-controlled newspaper, were described as "part of a Washington plot to destroy the constitutional powers of this nation."

Two of the men, apparently civilian U.S. Army employes, were spotted by Panamanian police while tearing down a "Yankee Go Home!" poster, the spokesman said.

One American civilian who did not want his name published said in an interview he was beaten, kicked, hit repeatedly with an electric cattle prod, robbed and denied access to U.S. consular aid by Panamanian police during his 24-hour detention.

At least 75 Panamanians were treated in hospitals this weekend for buckshot and beating injuries from Friday, medical authorities said.

Several leaders of the opposition National Civic Crusade were in hiding today because Alfredo Oranges, a top progovernment legislator, said he was filing criminal charges against them after his family's jewelry store was attacked during the frustrated demonstrations.

The small store belonging to Oranges' wife was broken into and ransacked by a dozen antigovernment demonstrators Friday afternoon, a witness said. Oranges, a member of the Panamanian Defense Forces' Democratic Revolutionary Party, blamed the crime on a Christian Democratic legislator, Guillermo Cochez, and three Crusade leaders, Aurelio Barria, Cesar Tribaldos and Eduardo Vallarino.

Tribaldos and Vallarino learned yesterday that police had orders to arrest them and sought refuge away from their homes, relatives said. Cochez remained in public and accused the government of sponsoring recent violence.

In this small, generally peaceful nation of 2 million, incidents of property damage have caused great alarm. Even progovernment Panamanians, including Oranges, recoiled in shock when gunmen who appeared to be connected to the military burned and looted a luxury department store belonging to opposition newspaper publisher Roberto Eisenmann July 2.

Oranges, surveying smashed display windows and upturned counters in his wife's store, estimated damages at $100,000.

Oranges acknowledged that none of the four opposition leaders he had blamed was at the store during the break-in, but said they had incited their sympathizers to disobey the law.