Jose Sarney, the new president of Brazil, has criticized the "paradoxical" position of developed countries that demand that poor nations increase exports to generate revenue needed to repay debts, then bar those exports with protectionist measures.

In an interview in his offices here last week, Sarney also said that the country is ready to enter serious negotiations with the International Monetary Fund and its creditor banks and might drop its opposition to a new round of multilateral trade talks. Brazil and India had resisted the talks, which were proposed by the United States last spring.

Last March, Sarney became Brazil's first civilian president in 21 years when his running mate, president-elect Tancredo Neves, died before he could be sworn in.

Sarney will make his international debut Monday in an address at the opening session of the United Nations General Assembly. The Sarney speech is expected to focus on economic problems.

Brazil, with more than $100 billion in foreign debt, is the biggest foreign borrower among the developing countries. It fell out of compliance with its IMF economic program last winter and since then has barely negotiated with either the fund or the banks about stretching out repayment of its billions of dollars of maturing loans.

Sarney said he would not agree to an IMF economic program that would push Brazil into a recession. But unlike the military government that preceded him, which regularly broke its IMF compacts, he said any agreement Brazil reached with the IMF would be one it could keep.

Sarney was adamant that countries should keep their markets open to Brazilian exports to enable it to earn enough money to pay its $10.5 billion yearly interest bill.

He said that protectionism has exposed Brazil to a "vulnerability that fills us with profound disquiet."

President Reagan's decision not to impose quotas on imports of shoes from Brazil and four other nations was greeted here as an important bilateral victory. But Sarney defended Brazil's bars on foreign access to its market for small computers, saying that they fall well within international guidelines for protecting emerging industries. The U.S. government is investigating Brazil's computer market.

Sarney suggested that Brazil would seek to take "joint positions" in consultation with other Latin American countries, but gave no specifics on how this would be done.