Oil ministers from the Organization of Petroleum Exporting Countries, struggling to recapture control of the world oil market, today began considering a new round of price cuts that would bring the cost of their oil more in line with free market levels.

The 13 ministers, meeting only two weeks after a session in Vienna collapsed after fruitless haggling about price and production levels, decided to postpone discussion of new output quotas until autumn.

Instead, they will concentrate on finding a new pricing structure for light and heavy oils.

Saudi Arabia's Ahmed Zaki Yamani warned his colleagues that the desert kingdom would no longer serve as the swing producer, adjusting its oil flow to control prices, delegates said.

Saudi Arabia has slashed output to a 20-year low of 2 million barrels a day in a vain effort to soak up the global oil glut and prop up prices.

Yamani also contended that Saudi Arabia and Kuwait, two major producers of heavy oils, must insist on lower prices for heavy grades because they were steadily losing customers who found much cheaper supplies on the "spot" market.

But light-oil producers, such as the United Arab Emirates, Algeria and Libya, have strenuously objected to more favorable treatment for heavy crude because their countries would suffer most from any expansion of the price gap between different grades of oil.

Many OPEC members fear that a new wave of price reductions would only exacerbate the pressures on the market without stimulating demand, particularly if governments in consumer countries impose an import tax on oil to preserve conservation efforts.

The protracted conflict within OPEC has assumed strong political overtones because the poorer, more populous OPEC members are bearing enormous social and economic burdens due to falling oil prices. They hold little sympathy for the plight of the rich sheikdoms.

Nonetheless, Saudi Arabia, with its ability to flood the market and drive down prices by pumping as much as 10 million barrels a day, still retains overriding influence in setting the OPEC agenda.

Yamani said today that he believed lower heavy crude prices were "a must" at this meeting.

The Saudis also have warned that they will not hold their output down to such low levels for long. Yamani told the ministers in Vienna that Saudi Arabia wants to pump its alloted share of 4.35 million barrels a day under the OPEC's total production ceiling of 16.5 million barrels.

Because of Saudi restraint, OPEC's output is now judged to be 14.5 million barrels, less than half of the 31 million daily barrels the cartel was churning out at its peak in 1979.

With non-OPEC producers like Britain, Mexico and the Soviet Union pumping at maximum capacity, the cartel's share of the world market has shrunk to one-third.

At the Vienna meeting, the 13 ministers pledged that their countries would scrupulously adhere to official quotas and prices in order to reassert discipline over the market.

But such vows have been repeatedly broken in the past. Members have offered hidden discounts or concluded barter arrangements in desperate ploys to sell more oil. Last week Nigeria and Canada reached agreement on an oil-for-goods deal worth an estimated $2 billion.

The "cheating" has become so rampant that as much as 80 percent of all OPEC oil is now believed to be traded below the cartel's fixed prices. As a result, Saudi Arabia, which unlike other members insists on selling its oil at the official rate, has come under heavy pressure to cut prices.

The Saudis have threatened to begin pumping their full quota, or 2 million barrels more than now, unless the cheating stops. Saudi sources said the kingdom is likely to make its next production decisions in September, based on an assessment of OPEC behavior.

A production hike by Saudi Arabia of 2 million barrels a day in a surplus market could drive prices down to $20 a barrel from the current average of $26, oil traders say.

Riyadh has been forced to dip into its financial reserves by as much as $1 billion a month to make up for lost oil revenues in paying for its continuing development projects. The Saudis are said to possess $100 billion in reserves, but half of that sum is tied up in commitments not easily liquidated.

Other countries also have signaled their intention to produce more oil because of economic pressures. Iraq, Ecuador and Gabon have said they intend to raise output regardless of their fellow members' views.

But the most important factor in undermining the cartel's ranks is the need to compete with price cuts offered by rival non-OPEC producers. Two weeks ago, non-OPEC Mexico, the world's fourth largest producer, announced a series of price cuts expected to force Venezuela, a key member of the cartel, to follow suit.

Similarly, Nigeria has been compelled to abandon the OPEC price structure in order to stick to the lower prices charged by outside producers Britain and Norway. The three countries compete for the same customers of their light crude oil.