Representatives of Third World nations in the International Monetary Fund have called on world leaders to enforce greater stability of their exchange rates, using "target zones" if necessary.

In a target-zone system, major countries agree to take steps to keep the exchange values of their currencies within a predetermined range.

The suggestion runs counter to the conclusion of the Group of 10 major industrial nations at a meeting June 21 in Tokyo that target zones are "undesirable . . . and impractical."

Nonetheless, it is expected that the possibility of target zones will be debated at a meeting of the IMF's Interim Committee in Seoul on Oct. 6, prior to the annual meeting of the IMF and the World Bank. It is one of many issues on which the Third World countries and the wealthy nations will have divergent views.

The Third World's suggestions on improving the international monetary system were produced by deputies of the so-called Group of 24, which represents all of the Third World nations in the IMF. The report, dated Aug. 23, was made available yesterday by the IMF.

The report agrees with a companion document, produced for the Group of 10 by its deputies under the leadership of Italian Central Bank Director Lamberto Dini, which says that the present floating-exchange-rate system has not lived up to expectations. A main weakness cited by both reports is that volatile exchange rates can discourage trade and investment.

But whereas Dini's report for the Group of 10 concluded that the present system "remains valid and requires no institutional change" and that there is no viable alternative to it, the Group of 24's report called for action.

That report said that exchange-rate volatility had been especially harmful to the poorer countries and that "it is necessary to devise an exchange rate system to overcome the recognized rigidities of the par value system and the destabilizing uncertainties of floating rates."

The Third World nations contend that adoption of target zones could help achieve that objective, but they acknowledge that the proposal "needs to be further studied and pursued in order to gain general acceptance."

During the Group of 10's discussions in Tokyo, the idea of target zones was advanced by France, which argued that, as the targeted-exchange-rate zones were introduced, they would touch off consultations among the key countries and lead to desirable links between domestic policies and exchange rates.

But the majority of those participating in the discussions, including Treasury Secretary James A. Baker III, responded that it would be difficult to agree on the zones, and that, even if agreement were reached, there still would be uncertainty about how to maintain them. "Markets would inevitably test the zones, thereby adding to instability, and efforts to maintain exchange rates at levels incompatible with market sentiment could prove costly and ultimately unsuccessful," the Group of 10's ministerial report said.

Another major point of the Group of 24's document is that the IMF, which doesn't hesitate to pressure Third World borrowers to conform to its austerity demands, fails to lean heavily on the richer nations, which the Group of 24 holds responsible for "misalignment" of currencies.

"Fund surveillance has to date been largely ineffective over the major industrial countries whose actions have substantial spillover effects on the world economy," the Group of 24's report said.

"As a result of this basic asymmetry in the fund's surveillance function, the international adjustment process has been seriously biased," the report said. "The deficit developing countries have been faced with harsher adjustment, and the world economy with a lower level of activity, than would otherwise be necessary."

The Group of 24 also:

*Repeated its demand for an annual allocation of at least $15 billion worth of special drawing rights, the IMF's "paper gold" that is convertible to hard cash.

*Suggested that because the Eighth Review of (IMF) Quotas -- the IMF's main source of funds -- is below needs, an early start be made on a Ninth Review.

*Demanded a 50 percent voice -- instead of the present 38 percent -- for the Third World nations in the IMF weighted voting system.

*Urged restoration of $3 billion in funds for the World Bank's subsidized lending program through the International Development Association, bringing it to the $12 billion level of the last three-year program.