The finance ministers and central bankers of leading nations yesterday began a four-day series of meetings to explore possibilities for additional international economic cooperation.

Netherlands Finance Minister H. Onno Ruding, who is chairman of both the Group of 10 industrial nations and the International Monetary Fund's policy-making Interim Committee, told reporters "it is unlikely there will be much consensus or progress" on international monetary reform issues.

He said there is less urgency on the question of stabilizing exchange rates, in part because the dollar has declined since last September when the nations known as the Group of Five decided to intervene to bring down the value of the dollar.

"And I just don't see support for target zones . . . which would require an enormous commitment of national reserves," he added. Under a target zone system -- advocated by France -- countries would agree to keep their exchange rates within a given range. He cited opposition to target zones from other European countries, Japan and the United States.

But Ruding predicted there will be growing support at later sessions this week for a new and more powerful "surveillance" role for the IMF, which would give it the authority to advise the United States and other major powers on their domestic economic policies.

In a communique' issued after a lengthy evening session, the G-10 supported the "need to strengthen surveillance," and asked the IMF to prepare a study on various indicators, including exchange rates, that the IMF might use in assessing individual countries' performance.

The G-10 also reiterated the central conclusion of its report on monetary reform presented at the annual meeting of the IMF and World Bank last year in Seoul. That endorsed retention of the floating rate system, but recommended improvements.

Meanwhile, Treasury Secretary James A. Baker III, Federal Reserve Board Chairman Paul A. Volcker and their counterparts from West Germany, Japan, France and Britain -- known as the Group of Five -- met secretly at the Treasury Department, and adjourned without an announcement.

In an effort to preserve a low profile for the G-5, officials would not even admit the meeting had taken place.

On the agenda of the secret meeting was a discussion of the impact on the global economy of falling oil prices and interest rates, and the question of when and how to transform the G-5 into a group of seven by adding Canada and Italy.

An Italian government representative, referring to the G-5 meeting at the Plaza Hotel in New York in September at which the small group decided on its own on joint intervention to depress the dollar, said, "We can't let that happen again."

Like other governments not involved in the decision, Canada and Italy were affected by the decision to intervene to boost nondollar currencies.

West Germany and Britain object to including Canada and Italy in the G-5, fearing that expansion would dilute the "clubby" atmosphere in which sweeping decisions can be made. But President Reagan promised Canadian Prime Minister Brian Mulroney that he would support the move.

Later, Baker and the ministers from the four other G-5 countries joined the ministers from Canada, Italy, Sweden, Switzerland, Belgium and the Netherlands in the G-10 session.

Prior to last night's G-10 meeting, Ruding already had conferred with many of the other leading finance ministers, including Baker. He said the "the world economic outlook is certainly better" than it was last October at the annual meeting in Seoul.

He attributed the improvements largely to the sharp drop in oil prices, which he said "has had a favorable impact on industrial countries as well as Third World countries." He also said "the more balanced situation on exchange rates" and a drop in interest rates also contributed towards a solution of the Third World debt problem.

In contrast to Ruding's relative optimism on the global economy, the Group of 24, which represents Third World countries in the IMF, issued a communique that not only expressed "serious misgivings" over the world economic outlook, but singled out the collapse of oil prices as the main culprit.

The poorer nations said the oil-price decline will have an adverse impact on the ability of oil-exporting countries "to sustain development and meet debt-service payments." Ethiopian Finance Minister Tesfaye Dinka, chairman of the G-24, told reporters not only would Third World debtor countries that sell oil lose revenue, but the Organization of Petroleum Exporting Countries, which had extended aid to some poor countries, probably would have to reduce that assistance.

The G-24 also urged a new issue of at least $15 billion in the IMF's paper currency, special drawing rights, but Ruding said flatly that it doesn't have general support.