MANAGUA, NICARAGUA, FEB. 1 -- Vice President Sergio Ramirez today announced a six-week "national electricity emergency" during which many of Nicaragua's largest factories will be closed, government offices will work only half days, and power will be cut for at least three hours a day to homes nationwide.

The government's decision to expand a limited power rationing, which took effect last month, came as a result of losses inflicted on key agricultural harvests by those cutbacks.

Under the new program electricity is to flow without interruption to sectors that earn foreign exchange: coffee and sugar mills, banana and fish processing plants, rice irrigation pumps and meat freezers.

Nicaragua is at the height of its harvest season. The nation of 3.4 million depends almost entirely for its $240 million annual income on agribusiness exports.

Workers in some of Nicaragua's main textile, chemical, cooking oil, soft drink and shoe factories will be idled for as long as three weeks as an energy-saving measure, Ramirez said. They will receive some pay and will not be laid off, he promised.

Employees of ministries and other agencies of the government, which is by far the largest single employer, will start work at 8 a.m. and go home at 1 p.m. to avoid enduring the sweltering afternoon hours without air-conditioning.

Nicaragua's sole, governmental television station will cut back its programming to four nighttime hours, said Ramirez, who is the acting head-of state until President Daniel Ortega returns tonight from an eight-day European tour.

Ramirez blamed the crisis on a string of recent sabotage actions by antigovernment rebels, known as contras, who blew out electrical towers across northern Nicaragua and crippled a small power plant during Christmas-time attacks in a north-central mining region.

The attacks aggravated chronic maintenance shortfalls in two major Managua generators due in part to the three-year-old U.S. trade embargo, which made spare parts hard to come by, Ramirez argued. The plants will be down for major repairs until mid-March. Ramirez estimated it would take $40 million to bring Managua's facilities up to date.

Energy Minister Emilio Rappaccioli indicated Managuans can also expect more frequent and prolonged water cutoffs during the emergency. Water taps are already dry two days a week in the capital.

In the countryside, Ramirez said, the government remains 6,000 coffee pickers short of the work force it needs to bring in the harvest.

Ramirez, a self-described moderate among the highest Sandinista officials, appealed to Nicaraguans' "patriotic good will" to withstand the inconveniences. He rejected a reporter's suggestions that the rationing will further erode support for the government.

"Nicaragua is being assaulted from all sides by a foreign aggressor," he said, referring to the United States. "But our people have tremendous moral reserves. In all these years of war the national consensus in favor of our revolution has not been destroyed."

The power rationing will limit the impact of one concession the government made under the terms of a regional peace plan: the reopening last week of eight radio news shows. The unpredictable power cuts mean that the stations which broadcast the independent news hours often will be off the air when the shows are scheduled.