A 23-year-old Mozambican Air Force pilot today flew a Soviet-made Mig 17 fighter jet into neighboring South Africa and asked for political asylum.

"I came to South Africa because I don't agree with Frelimo policy," Lt. Adriano Francisco Bomba told reporters, who met him at Hoedspruit Air Force Base in the north of Transvaal Province about 55 miles from Mozambique.

Frelimo is the ruling Marxist Party of Mozambican President Samora Machel, who has led the country since its independence from Portugal in 1975. The Soviet Union has helped train and equip Mozambique's military force.

A communique by the Mozanbique Air Force confirmed the defection and said it "is investigating the causes of this event."

"In Mozambique after six years I can't see progress. The way of life in Mozambique is getting worse and worse, and I'm tired of that," Bomba said in fluent English. "When I arrived, the treatment the gentlemen here gave me was very good. Now excuse me, I must leave."

Reporters were unable to question the defector, who was wearing a comourflage uniform, so it is not known how he learned English.

"We'll keep him safe until the right authorities decide what to do with him," Air Force chief of intelligence Brig. Gen. Dries van Der Lith said. "Intelligence will talk to him to find out what made him come here."

The government has not said whether it is prepared to grant Bomba asylum, but it is unlikely it would refuse. Despite their extensive transport and trade ties, relations between South Africa and Mozambique are very strained.

The Mozambicans have accused South Africa of supporting a rebel guerrilla organization that is tying down government troops in some parts of the countryside. It is also still smarting from the raid by South Africans last January on an anit-South African guerrilla organization's offices in the capital, Maputo.

Bomba's vocal dissatisfaction with Machel's rule will no doubt be regarded here as proof of the hardships faced by those who live in neighboring black-ruled states which adopt socialist or Marxist policies.

The reasons for Bomba's flight may, however, also be related to the recent trial on charges of sabotage, espionage and armed rebellion of four Mozambicans, one of whom was accused of spying for South Africa. Two of the men received death sentences.

Other Mozambicans were arrested last March when four U.S. embassy officals were accused of being CIA agents and expelled from Mozambique.

Bomba flew his plane at low altitude to escape detection by Mozambican authorities. Once over the border he was intercepted by two South African Mirage F1 fighters, and indicated by signals that he wanted to land.

"He didn't show any aggressiveness, so that's why they decided not to shoot him down," van Der Lith said.

"He said he tried to make radio contact but didn't. Either we weren't on the same frequency or the radio didn't work.Probably the radio didn't work," van Der Lith said.