Romania has informed its major Western creditor banks that it will withhold debt repayments this year of over $1 billion until a rescheduling agreement is worked out, bankers said today.

Romania, which only last month signed an agreement in London to stretch out payments on $2.3 billion of 1981 and 1982 debt to banks, said last spring it should be able to resume payments as normal in 1983.

But bankers said today the country's foreign trade bank had invited a negotiating group of nine leading creditor banks to start talks this month on rescheduling 1983 debt. Two U.S. banks--Manufacturers Hanover Trust Co. of New York and Bank of America of San Francisco--are members of the group, which was the same body that completed the 1981-'82 refinancing plan.

The move--which follows last week's decision by Brazil, the world's most indebted country, not to repay medium and long-term loans falling due from today--will increase the pressure on the world's commercial banks as they struggle with the international debt problem. Other countries whose debt principal will not be paid this year include Mexico, Argentina, Costa Rica and Bolivia.

Meanwhile, Associated Press reported yesterday from Sao Paulo, Brazil, that a newspaper there had published what it says are excerpts from the letter of intent the government delivered to the International Monetary Fund, requesting $5.9 billion in loans and defining economic policy to be followed through 1985.

The excerpts give some new details, but the main policy decisions already have been made public, particularly the decision to continue mini-devaluations of the cruzeiro, Brazil's currency, against the dollar, and to impose austerity.

Romania owes Western creditors, including governments and international organizations such as the IMF and World Bank, just over $10 billion and is due to repay about $1.45 billion this year. The country is pledging to maintain 1983 interest payments, which it has estimated will total $735 million.