Michel Camdessus, managing director of the International Monetary Fund, yesterday endorsed a form of voluntary debt relief for Third World borrowers, calling on debtor countries and commercial banks to seek "imaginative" new solutions to the debt problem.

In a speech to the opening session of a two-day conference on debt sponsored by the Overseas Development Council, Camdessus studiously avoided the controversial term "debt relief."

But he suggested that lenders and debtor nations should "share in a mutually-agreed fashion the existing discount on debt." Because of current economic problems, loan contracts made by many Third World countries can be bought at a large discount from face value. But while the purchaser of such loans may enjoy a bargain, the debtor country is still obliged to meet the original terms.

An IMF source explained that Camdessus, in speaking of "sharing the discount" was not referring to large discounts now available in the secondary market, but to "market-based" discounts that might be arrived at in negotiation between a bank and a debtor nation.

Although Camdessus was not endorsing any particular debt relief plan, an elaborate new proposal along not-dissimilar lines was outlined last night to the ODC conference by American Express Co. Chairman James D. Robinson III.

Camdessus stressed that commercial banks must "do more" in extending new loans to the hard-pressed Third World countries.

He said that imaginative schemes that are market-based -- such as the current Mexican scheme -- but "also any other proposal that would be market-based and would share in mutually agreed fashion between debtors and creditors the discount on debt and the benefits of adjustment could only be welcome."

The Mexican scheme to which he referred is a plan by which Mexico proposes to exchange loans, at a discount, for long term securities backed by zero-coupon bonds that Mexico purchased from the United States.

In his speech, Camdessus offered no specifics. But in answer to a question following his address, he said: "We can easily find instruments -- and the market will find instruments -- to share between the bankers and debtors the discount, on the one side; and also the benefit of adjustment on the other side."

He said that these "instruments" would be developed in the coming months, and that if there is sufficient economic growth and open markets in the richer nations, "I think we will have some light at the end of the tunnel."