The Mexican government announced last night that Mexico would lower modestly the price of its light crude oil in line with last week's reductions by the Organization of Petroleum Exporting Countries.

Mexico cut the price of its Isthmus crude by $1.25 a barrel to $27.75 a barrel. It left unchanged the price of its heavy crude, called Maya, at $25.50 a barrel. Light crudes cost more than heavy ones because they yield more gasoline when refined.

The price cut, which mainly will benefit Japan, is too small to seriously hurt Mexico's debt-burdened economy, according to government officials and foreign economic specialists. It will cost Mexico $300 million a year in lost revenue, which is equivalent to only 1.9 percent of the nation's total petroleum income, according to a joint communique' by the Energy Secretariat and Pemex, the state oil company.

"The reduction in the price of Isthmus affects us, but not catastrophically. The contraction in foreign exchange income that it implies is manageable for our economy," the communique' said.

The relatively modest size of the price cut signaled that Mexico is continuing its longstanding policy of avoiding a price war with OPEC. But Mexico might lower its price again if OPEC members steal its customers by granting under-the-table discounts, industry analysts said.

"There may be a gradual reduction in stages," a oil expert said. He said that Mexico should have reduced its price by $2 a barrel to protect itself fully against OPEC discounters, but he added that "the real crunch" would come only in spring, when oil prices generally weaken as warmer weather reduces demand for heating oil.

Mexico is the world's fourth-largest oil producer and the largest single supplier to the United States. The United States mainly buys Mexico's heavy crude, Maya, however, while Japan is the main purchaser of Isthmus.

Mexico produces 2.7 million barrels of oil a day, of which it exported an average of slightly more than 1.5 million barrels a day last year and consumed the rest. Of the exports, 55 percent was Maya crude and 45 percent was Isthmus.

Mexico was able to keep the price of Maya crude unchanged because the current oil glut mainly affects light crudes such as Isthmus. U.S. demand for heavy crude remains strong in part because Gulf of Mexico refineries in recent years have installed new technology for processing heavy crude.

The Mexican communique' appeared to be deliberately vague about how much oil Mexico intended to export this month. It said that it was ending a commitment -- undertaken in November to help OPEC cope with the oil glut -- to reduce its exports by 100,000 barrels a day. But it also pledged not to increase exports.

The government apparently wished to reassert its long-term target of exporting 1.5 million barrels a day while assuring OPEC that it would cooperate in stemming a further slide in prices.