VIENNA, Austria--OPEC negotiations to clinch an oil price and production pact stalled yesterday amid conflicting signals about the outlook for a final accord.

A planned meeting of all 13 oil ministers was put off, and Algerian Oil Minister Belkacem Nabi said the ministers would meet today.

Gabon's oil minister, Etienne Guy Tchioba, said the cartel leaders might have to rework a tentative accord, reached Saturday, to retain the $18-a-barrel oil price and renew OPEC's existing set of national oil production quotas.

Analysts have said the agreement, if approved, would lead to an immediate decline in world oil prices of as much as $2 a barrel, translating to a drop of about 5 cents a gallon in retail prices of gasoline and heating oil in the United States.

Tchioba said that some delegations, which he did not identify, feared the prospective deal would be viewed negatively by oil traders and result in a new price decline.

"We realized that the [production level] ceiling was not credible for the market," he said.

But a conference source, speaking on condition of anonymity, said the only obstacle to ratifying the tentative agreement was a reluctance by Iranian authorities in Tehran to sanction the deal.

Iran had been insisting that the $18 price be increased by $2.70.

Iraq, locked in a 7-year-old war with Iran, is not expected to sign the agreement because it wants to raise its production quota to Iran's.

Tchioba said the deal was virtually set Saturday, but a debate broke out in the Organization of Petroleum Exporting Countries over how long the accord should last.

Some wanted the $18 price to hold throughout 1988, while others wanted to review it during the year, he said.

Analysts said the tentative deal's major weakness was that it was unlikely to halt overproduction by OPEC members such as Iraq and the United Arab Emirates.