Led by an American, Libya's war on deadly flesh-eating screwworm flies is about to take to the skies.

After months of delays, the aerial release of millions of sterilized flies will begin early next week, according to an official from one of the U.N. agencies leading efforts to wipe out the parasite.Test releases had been scheduled for August, with hopes to begin full-scale release in January.

The program has been held up in part by initial U.S. refusal to deal with Libya and by the slow response from several nations to deliver on aid pledges.

Officials are especially anxious since infestation by the fly, which attacks livestock, wildlife and humans, has been reported moving toward Egypt these days, borne by westerly winds.

Experts have expressed fears that the fly could move quickly down the Nile River Valley into Central Africa, threatening exotic wildlife as well as livestock.

The fly was first spotted in Libya in July 1988, and for most of the time since has been living in a narrow band in northern Libya.

The experts say that the only way effectively to eradicate the fly is by releasing tens of millions of flies sterilized in a special facility in Mexico that uses patented U.S. technology. The flies mate with flies already in the area, the matings yield no offspring and the insect eventually dies out.

A U.S. entomologist employed jointly by the U.N. Food and Agriculture Organization and the International Atomic Energy Agency is in Tripoli to oversee the eradication efforts, said Bjorn Sigurbjornsson, in a telephone conversation from the IAEA's Vienna offices.

The agency is involved because radiation is used to sterilize the flies.

U.S. sanctions, prohibiting Americans to travel to Libya or do business with it, complicated planning for eradication. The measures date back to 1986, when then-President Reagan accused Col. Moammar Gadhafi's regime of sponsoring terrorism.

Last spring, an FAO official announced that the United States had reversed its position and agreed to let U.S. technicians employed by international organizations travel to Libya on U.N. passports. U.S. expertise is considered crucial to the success of eradication.