Brazil has finished its large-scale development plan and will not need to borrow additional money from U.S. banks, President-elect Tancredo Neves said yesterday. However, old loans and the interest on them remain "very burdensome," he added.

Neves talked with President Reagan for 20 minutes and breakfasted with three Cabinet secretaries as part of his three-day visit to the United States. Talk of Brazil's $100 billion foreign debt was "rolled into the whole economic scene" in the discussions, according to a senior U.S. official who briefed reporters on condition he not be identified.

The official said Neves did not ask for help nor was he offered any. "It was basically an opportunity for him to take the measure of the president and the Cabinet officers, and vice versa," the official said.

The talks were "substantive, but not specific," he added. During a photo session, Reagan remarked to Neves that not only were they about the same age, but both their birthdays are in February. Reagan will be 74 next Wednesday, but Neves' 75th birthday is not until March 4, Brazilian officials said.

Both Reagan and Secretary of State George P. Shultz brought up U.S. policy in Central America in order to outline it and express support for the Contadora regional peace process, but they did not ask for any action by Brazil, the senior official said.

Others at the breakfast included Defense Secretary Caspar W. Weinberger, Commerce Secretary Malcolm Baldrige and Special U.S. Trade Representative William E. Brock. Neves also met with congressional foreign policy committee leaders.

Neves is to take office next month as Brazil's first civilian elected president after 21 years of military rule. One of 12 children of a poor shopkeeper, he has 50 years of political experience in congress and as prime minister before 1964, and it is generally agreed that he will need it during his six-year term.

"We no longer need to borrow new money," he said in response to questions after a speech to the National Press Club. "We have concluded all the major public works that were begun, and we have to hold back on new debt." He called U.S. interest rates "taxation without representation," noting that every percentage-point increase costs Brazil $400 million.

On arriving here Thursday night, Neves said Brazil "does not have any political problems with the United States, only economic problems -- interest, trade, the debt and protectionism."

Although trade with Brazil is less than 2 percent of all U.S. commerce abroad, it is Brazil's primary source of overseas income, and provided $6 billion toward Brazil's trade surplus last year.

Neves was expected to meet today with officials of major national and international banks to discuss the country's 220 percent inflation rate and 40 percent unemployment, which reportedly have stalled agreement on a loan renegotiation package. He announced at the press club that he expected $65 billion to $70 billion of it to be rescheduled over a 15-year period.

"We ask that the International Monetary Fund show itself more sensitive and understanding toward the problems of developing nations like Brazil," he said.

If the United States were to allow Brazil's ethanol fuel, produced from sugar cane, to be marketed here, "that would be one of the best presents you could give to strengthen our economy," he said. However, the subject did not come up in the talks, he added.

Neves met with heads of state in Italy, France, Portugal and Spain before coming here; he is scheduled to leave Sunday for Mexico and Argentina.