PANAMA CITY, JULY 30 -- Panama's banking system, a mainstay of its economy, is coming under increasing pressure as political opposition activities mount, and the government is feeling the effects of a default on loan payments to foreign governments, according to Panamanian economists.

A sharp increase in capital flight in recent days is adding to the pressure on Panama, which uses the U.S. dollar as its currency, but calls it the balboa. The flight of dollars increases the prospects that Panama could face a liquidity crisis, economists say, because the country cannot print more money.

"Yesterday was a hard day for the banking sector," said Aurelio Barria, the president of the Panamanian Chamber of Commerce and a leading opponent of military strongman Gen. Manuel Antonio Noriega. "We're extremely worried."

He added that some credits to the country have been "suspended." In part, this is believed to have resulted from a government decision in June to temporarily stop principal and interest payments on loans from foreign governments. These loans constitute a minor portion of Panama's estimated $3.8 billion foreign debt, but the decision, which amounts to a default in payments on them, is believed to have affected the confidence of commercial banks, which hold most of the loans to Panama.

Among the effects of the default are that letters of credit now are often not available, domestic loans are hard to find, some long-term loans are being called and national savings banks are requiring up to a 30-day notice for withdrawals, knowledgeable sources said.

According to Raul Mendez, an economist, banks yesterday experienced heavy drainage of deposits, contributing to bankers' concerns.

"The economy is going to keep deteriorating, social problems are going to grow and there's going to be more capital flight," he predicted.

While the Chamber of Commerce and many Panamanian businessmen and professionals oppose Noriega and want to step up economic pressure to force him to resign, they are also being hurt by the capital flight and banking system difficulties, political analysts said.

Since political turbulence erupted in early June following public accusations of corruption, election fraud and murder against Noriega by his former military second-in-command, an estimated $3 billion to $4 billion has left the country, economists said. The total assets held by Panama's 130 foreign and domestic banks was put at about $40 billion before the crisis began.

Following a call for anti-Noriega protests by the opposition National Civic Crusade, whose leaders come largely from the Chamber of Commerce, many Panamanians have been transferring their money from government banks to private institutions in recent weeks. Another phenomenon at work, economists said, is the increasing transfer of money from domestic banks to branches of foreign banks here. Some of that money is then being sent out of the country, the sources said.

Since banks resumed normal operations yesterday after a two-day general strike, foreign depositors have been flooding banks here with orders to transfer their money abroad, Panamanian sources said.

The country has no capital or foreign exchange controls, so information on capital flight and other banking matters tends to be sketchy. In addition, the Panamanian government and banking system traditionally have observed strict secrecy, restricting reliable information but making the country a haven for illicit funds.

The offshore banking operations and infrastructure here have made Panama the Latin American capital for the laundering of drug money, known here as "narcodollars."

According to government figures, banking, financial services and real estate directly employ about 9,000 people and account for about 7 percent of the country's gross domestic product.