Finance ministers from Latin American debtor nations will meet in emergency session this week amid signs that they may demand a dramatic reduction in the interest rates on their $360 billion in foreign debt.

Latin American financial and diplomatic sources said the nations may ask their bank lenders to reduce interest rates on the debt to levels that are lower than the cost of funds to the lending institutions.

Such a move -- whether agreed to by the banks or imposed unilaterally by one or more debtor countries -- could wreak havoc on the value of the $225 billion of Latin American loans on the books of commercial banks around the world. The remaining $135 billion in Latin American debt is owed to other governments or official institutions such as the International Monetary Fund and the World Bank.

This week's meeting was requested by Mexico, which has been financially devastated by the steep decline in the world price of oil. Last year, oil accounted for about 70 percent of Mexico's exports and nearly half its domestic tax revenue. At current prices, Mexican oil-export revenue could decline 40 percent or more from last year.

Although Mexico's problems are the most urgent in the region, Argentina will face serious financial difficulties later this year because grain prices have declined significantly and severe floods have wiped out a large portion of the nation's wheat planting. Grain is Argentina's key export.

Venezuela, another major oil exporter, joined with Mexico in calling for an emergency meeting of the key nations in the 11-member debtors group. But Venezuela, with massive reserves of dollars and a relatively small population, can weather the oil price decline better than Mexico.

A hard-pressed Mexico -- facing severe internal political and social pressure after nearly four years of recession and low economic growth -- could alter the relationship among the debtor nations, their bank lenders and the industrial governments. Mexico has been a conservative influence in all Latin American debt caucuses, and its seeming success in pulling itself out of economic difficulty undercut the posturing of more radical debtor nations such as Peru.

Peru has refused to pay more than 10 percent of its roughly $3 billion in export earnings to service its debt and has declined to negotiate with the IMF.

Also Tuesday, Peruvian banking officials reported that all of the nation's gold, silver and cash reserves had been withdrawn from U.S. banks in order to prevent the United States from freezing them.

Hector Neyra, general manager of Peru's Central Reserve Bank, said the transfer was made because of a "hardening in our relations with our creditors" over the repayment limits, the Associated Press reported. Peru's total international reserves are $1.5 billion.

"This year could be more crucial than 1982," the year Mexico ran out of money and triggered the debt crisis, according to a leading Latin American diplomat.

After nearly four years of austerity, the Latin American governments and their residents are weary of instituting measures to reduce economic growth to husband dollars to pay debt, the diplomat said.

There is also less room for banks and the debtors to change repayment schedules to ease the yearly payment burden, as they did in the early years of the crisis. Nearly all principal payments have been pushed off until 1990 or beyond, and banks can reduce their interest rates little more and still cover the cost of the deposits that fund Latin American loans.

"The obvious answer is more loans," said one key Latin American economist. "But most countries seem to be reluctant to borrow more just so they can pay their interest."

Uruguayan Foreign Minister Enrique V. Iglesias said it is possible that the debtor nations will seek below-cost interest rates, but said that Latin American countries would prefer to negotiate with the banks and the industrial governments rather than take unilateral measures to hold down their payment burden. Uruguay will host the debtor conference at the seaside resort of Punta del Este.

The debt crisis has worsened in the last year after substantial improvement in late 1983 and 1984. A strong U.S. economy in those years increased demand for the commodities that Latin America relies on for most of its foreign earnings. But U.S. economic growth slowed last year and other industrial countries did not pick up the slack.

Lower oil prices may stimulate economic growth in Europe, Japan and the United States, and again stimulate demand for commodities. But Latin American officials said the impact would not be felt soon enough to stave off this year's repayment problems.

U.S. Treasury Secretary James A. Baker III proposed an "initiative" in October to boost lending from commercial banks and development institutions to enable debtor countries to pay their foreign bills and resume the higher level of economic growth needed to support their growing populations.

But the recent plunge in oil prices -- coupled with the decline in the prices of most other commodities -- makes the three-year, $27 billion Baker plan appear far too small to most debtors.

In less than a year Mexico, with $97 billion in foreign debt, changed from a "model" debtor nation -- which was making progress in reducing domestic inflation and spending, building up foreign reserves and easily paying its $11 billion yearly interest bill -- to a nation in which nearly all international and domestic economic conditions are deteriorating.

Mexican President Miguel de la Madrid Hurtado warned in a television address to his nation last week that the country cannot pay all that it is supposed to this year. Its problems were compounded by a severe earthquake that struck Mexico City in September.

Latin American diplomatic sources said, however, that de la Madrid was careful, even in rhetoric aimed at a domestic audience, to avoid threats to take unilateral steps to ease Mexico's payments problems. All 11 debtor nations said at a meeting two months ago in Montevideo that they might have to take unilateral steps, such as reducing interest payments, if conditions did not improve.

Several debtor nations will benefit from the decline in oil prices. Ecuador, Colombia and Peru are oil exporters as well, and will feel the pinch of the price decline. But rising coffee prices, the result of a Brazilian drought, will offset some of the impact of lower oil prices for Colombia.