Roger Miranda Bengoechea, a former top aide to Nicaraguan Defense Minister Humberto Ortega who has become one of the United States' most valued defectors, is to receive $800,000 from the U.S. government in rewards, resettlement assistance and a contract for unspecified services, congressional sources said yesterday.

The amount is more than the Central Intelligence Agency generally pays high-level defectors, apparently reflecting U.S. delight with the defection Oct. 25 and his performance since then.

Other defectors have received more than $600,000 in lump payments or lifetime annual stipends, according to published reports, and some will receive considerably more, depending on how long they live. Many have been given far less.

Miranda, 35, defected on an official trip to Mexico City, leaving his former boss aboard Nicaragua's version of Air Force One.

Humberto Ortega later called Miranda a "little worm" and said he was "the most important betrayal" in the seven-year history of Nicaragua's leftist Sandinista regime. Since then, Miranda has appeared at dozens of interviews and news conferences orchestrated by the State Department to denounce the Sandinistas.

According to the sources, Miranda is to receive a lump sum of $500,000, plus $75,000 in resettlement aid and a five-year contract worth $45,000 annually, all from the president's contingency fund. The sources said they do not know what services he is to perform under the contract.

An administration official confirmed the payment's general outlines but said the financial agreement is tentative and could differ slightly from figures given by congressional sources.

The House and Senate intelligence committees have been briefed on the arrangements, and members of the traditionally close-mouthed panels would neither confirm nor deny the payments.

A major question is whether Miranda was offered the payment before or after his decision to defect. A State Department official insisted that Miranda did not know how much he would receive until Jan. 5, several weeks after he began his round of U.S. interviews.

"I can say categorically he was not contacted and did not contact any U.S. officials in Nicaragua," the State Department official said.

The official said that he could not confirm the amount of the settlement but that it is a "standard resettlement package" that would give Miranda a standard of living "roughly comparable to that he would have enjoyed in his country of origin."

High-ranking defectors generally can count on receiving $300,000 to $400,000 in various forms of compensation, although some particularly valued defectors received more.

Arkady Shevchenko, a Soviet diplomat who defected here in 1978 as U.N. deputy secretary general, reportedly received a $60,000 annual stipend. Former KGB officer Yuri Nosenko, who defected in 1964, reportedly was given a lump sum of $125,000 and more than $500,000 in consultant fees and other payments.

Miranda, who had access to high-level military and government secrets as Humberto Ortega's personal secretary, has alleged that the Sandinistas plan to use a regional peace plan as a cover to consolidate power and defeat the contra rebels.

Staff writers Joe Pichirallo and Lou Cannon and staff researcher Michelle Hall contributed to this report.