Alan Garcia, inaugurated as president today, declared that Peru will use no more than 10 percent of its export earnings this year to service a foreign debt already heavily in arrears.

Garcia, at 36 the youngest president in Latin America, also told the Congress that he would establish a commission empowered to negotiate with the radical Marxist Shining Path guerrillas that disrupted the five-year term of his predecessor, Fernando Belaunde Terry. He asked the commission to seek prompt trial or release of about 1,500 suspected guerrillas now imprisoned.

Security measures around the Congress building and the Presidential Palace were the strictest yet experienced in Peru. But last night, a car bomb exploded behind the headquarters of the Joint Chiefs of Staff, and sabotage attacks blacked out a quarter of Lima and several provincial cities.

Fires attributed to guerrillas formed hammer-and-sickle symbols on barren hills overlooking the capital.

Garcia won a sweeping electoral victory in April, taking positions consistently to the left of the government of Belaunde. Reasserting earlier unwillingness to seek the debt assistance of the International Monetary Fund, Garcia said he would deal directly with banks and countries that Peru owes about $13.5 billion.

Ten percent of Peru's current annual export earnings would be about $310 million, while debt service is calculated at about five times that amount for each of the coming five years. Officials indicated that Belaunde's government paid more than $1 billion annually before falling more than six months in arrears during the last year.

In a speech that sought to take the political initiative both at home and abroad, he said, "We will not accept impositions in economic policy." Declaring that his election "expresses the will of 20 million Peruvians and not the functionaries of a coldhearted international organization," he added that "Peru has one great, primary creditor, its own people, for whom the government will allocate the necessary resources to reconstruct its destiny."

Garcia went on to warn of a "harsh economic program" internally that would cancel unspecified tax advantages now provided for foreign oil companies operating in Peru's modest eastern fields.

Six popularly elected Latin American presidents attended the ceremony, as did U.S. Treasury Secretary James D. Baker III. The delegation flew back to Washington this evening after a brief meeting this afternoon with Garcia.

Garcia requested that visiting Panamanian President Nicolas Ardito Barletta convoke a Latin American summit in Panama to discuss regional issues. In addition, he proposed that the Contadora group countries should be reinforced by a Latin American front, "to guard Latin American sovereignty, which is at stake in Central America and Nicaragua."

Garcia also called for a regional agreement to reduce military spending and to put a freeze on arms purchases. As a first step, Garcia announced that Peru would take fewer than the 26 Mirage fighter-bombers that were ordered in late 1982 from France.

By the time Garcia had finished his speech, he had outlined to Congress six legislative bills to deal with corruption in public administration and the police forces, agricultural development, decentralization of public functions and business monopolies.

Following the inaugurual speech, Garcia swore in his Cabinet and was recognized as head of the armed forces. The military ruled for 12 years following a coup in 1968, and the last transfer of power from one elected civilian to another came in 1912.