MANILA, Philippines (AP) _ Even before the Persian Gulf War has ended, the Philippines is hoping to cash in on an anticipated economic boom by offering thousands of workers to help rebuild after the devastation.

''The crisis is now seen in the long term as providential to Filipino workers,'' Labor Secretary Ruben Torres told a Senate hearing recently.

But the official whose agency will lead efforts to find jobs says the government should temper its optimism. He says gulf countries may not have the money to hire foreign workers, or may have other spending piorities.

Torres predicted that 300,000 new jobs in construction and the service industry may be available to Filipinos in the gulf when the fighting stops.

Many foreign workers send money home to families and their remittances would be a major source of foreign exchange for this impoverished country.

Government planners had feared a gulf war would devastate the Philippine economy by driving up oil prices, drying up foreign exchange and depriving thousands of Filipinos of jobs in Saudi Arabia and elsewhere in the Middle East.

About 30,000 Filipinos fled jobs in Kuwait after Iraq invaded the emirate in August. An estimated 500,000 Filipinos work in the Middle East, including 390,000 in Saudi Arabia.

Looking to the future, the Philippines hopes to find more jobs for its people in Saudi Arabia, Kuwait and even Iraq. That would ease unemployment, predicted to rise from 8.4 percent to 13 percent this year.

Many Middle Eastern countries import workers because they have small populations or because they lack enough skilled workers.

During a recent speech, Foreign Secretary Raul Manglapus said the government would create an inter-agency committee to place ''Philippine resources and skills at the service of that region in even more volume and quality than they are serving it now.''

Foreign Undersecretary Pablo Suarez said the Philippines should establish labor agreements with all gulf nations on pay, tenure and improved working conditions.

Private job recruiters are also optimistic that the war will open up opportunities for Filipino labor.

Cita Garcia, president of the 200-member Philippine Association of Service Exporters Inc., predicted a job ''windfall'' reminiscent of the gulf boom years of the 1970s.

She expects Saudi and other gulf employers to favor Filipinos over Yemenis and Palestinians because they have sided with Iraq in the war.

''Something good must come out of this crisis,'' she said. ''This is the time that our government together with the private sector can negotiate for better terms.''

But Jose Sarmiento, administrator of the Philippine Overseas Employment Administration, said the government should be cautious in its projections.

Sarmiento said few new jobs may become available in Saudi Arabia because of the high costs of the war and an expected slump in oil prices when the fighting ends. He also suggested that the Saudis could redirect postwar spending toward weapons to maintain the balance of power in the gulf.

Western economists predict Saudi revenues, mostly from oil, may not exceed $12 billion for the first quarter of 1991 while spending could reach $30 billion.