World debt: How well can banks carry it?

Some developing countries and some communist nations owe so much money to Western banks that the question arises:

Will one or more of them default, triggering an international financial crisis that could send some major banks to the wall?

''[The chance of] a debt crisis triggered by the default of a major borrower, '' says Robert Solomon, guest scholar at the Brookings Institution, ''is certainly greater than zero, but not very large.''

''Default,'' says Lawrence B. Krause, senior fellow at Brookings, ''remains highly unlikely. But what about something less than a default? Could that be a trigger?''

If several major debtor nations escaped outright default, but faltered on servicing their outstanding debt - that is, failed to make interest payments - ''this would impinge on the cash flow of creditor banks.''

This, too, says Mr. Krause, would be unlikely to lead to a major crisis, assuming that Western banks continue to cooperate on specific problems. ''Any weakening of cooperation (among creditors),'' he warns, ''would increase the danger.''

Roughly 500 US, European, and other banks, for instance, work together to help Poland avoid default.

Also lending stability to the scene, Mr. Krause notes, is the presence of ''lenders of last resort'' - the International Monetary Fund, the World Bank, and central banks of creditor nations.

''I don't think we're very close to a breakdown of the financial system,'' says C. Fred Bergsten, director of the Institute for International Economics and a former assistant secretary of the Treasury.

''What is happening,'' he adds, ''is that the growth rates of debtor nations are very severely constrained because of their debt burdens.''

''Brazil,'' says Mr. Solomon, ''after economic growth of 5 to 10 percent yearly in the 1970s, suffered a 3.5 percent decline in 1981.''

More than 30 percent of the money Brazil earns from exports goes for interest payments on its nearly $50 billion worth of debt to foreign banks. Other major debtors - Mexico, Argentina, Poland, East Germany - have similar debt service problems.

''The whole picture would improve markedly,'' Solomon says, ''if world inflation dropped, interest rates went down, and there was faster growth in the industrial world. This combination would do wonders for developing countries.''

Each of the three largest Latin American debtors - Mexico, Brazil, and Argentina - owes a great deal more money to foreign banks than any communist nation, including Poland. Latin American debtors, experts agree, are in a better position to work themselves at least part way toward solvency, because of their ability to export a wide range of products.

Brazil, says Mr. Bergsten, has a proven ''track record on the export of manufactured goods,'' resulting in a trade surplus in 1981. The nation's broader current account measurement, embracing services and capital flows as well as trade, ended up $13 billion in the red, mostly because of $10 billion spent on interest payments.

''Brazil,'' says Solomon, ''has cut imports, boosted exports, and is likely to continue to do so. So a debt crisis for Brazil is unlikely.''

Mexico also suffered a $13 billion current account deficit last year, but has oil to export. Of the three, Argentina appears least able to solve its debt problems, given political and economic uncertainties following the Falklands war with Britain.

Mr. Krause says that ''debt is not a problem for anyone able to respond with exports'' - something which Poland and other East European nations find it hard to do.

Communist manufactures often fail to match the quality of similar exports from Japan, Europe, or the United States - at least over a broad range of goods.

Debt owned to private banks by major borrowers (in billions of dollars) 1975 1978 1981 Latin America: Brazil 14.8 31.7 49.7 Mexico 13.5 23.2 55.3 Argentina 3.2 6.7 22.9 Eastern Europe: USSR * 12.8 15.9 Poland * 11.7 14.7 E. Germany * 6.2 10.1 * not available Source: Bank for International Settlement