A prolonged shutoff of Iranian petroleum exports would have a significant effect on oil supplies, but the world market can withstand a brief halt in Iranian supplies, oil industry officials said today.

"The key question is how long they will continue to have this relatively low export level," said Gary Ross, a senior economist with the Petroleum Industry Research Foundation, an industry-supported organization.

The continuing violence in Iran has halted oil exports from the country, which is normally the world's second-largest oil exporter, shipping 6 million barrels a day. Western Europe, Israel and Japan are all major buyers of the Iranian oil.

The United States imported an average of 848,000 barrels of oil a day from Iran during the first nine months of the year -- 4.5 percent of the country's oil consumption and 10.7 percent of its imports.

It takes about 30 days to ship Iranian oil to the United States, so oil from that country will keep arriving for several weeks even if the disruptions continue.

During much of November and December Iranian exports were reduced to half their normal levels or less, but the industry was able to make up the difference, mostly with increased exports from Kuwait and Saudi Arabia, Ross said.

"In the short run, they can make it up even with zero production [in Iran]," Ross said. He added that a cutoff for a month or two would "have a real tightening effect" on oil supplies.

The Organization of Petroleum Exporting Countries has announced its prices for all of 1979, and Ross said oil industry experts think the oil exporters would stick to those prices even without Iranian supplies.

Ross noted that whether the shah retains power or another government takes over, "it is clearly in their interest to raise exports back to normal."

Some of the major importers of Iranian oil include:

Israel -- Officials in Jerusalem said today the country was in no danger of running out of oil despite the crisis in Iran, which usually supplies around 70 percent of Israel's oil requirements.

Energy Ministry officials said Israel was buying oil from Mexico at a 5 percent premium over the price of Iranian oil. Israel imports about 7.3 million metric tons of oil at an annual cost of more than $700 million.

Under the 1975 Israeli-Egyptian interim accord, the United States undertook to supply Israel with oil for five years in an emergency, the officials pointed out.

France -- The United Arab Emirates assured France that it will attempt with other oil-exporting states to compensate for any French oil shortages resulting from the loss of supplies from Iran.

Oil Minister Mana Al-Oteiba gave this pledge to visiting French Foreign Minister Jean Francois-Poncet when they met in Abu Dhabi, aides of the minister said.

Iran supplied France with 5 million metric tons of crude oil during the first half of this year, accounting for 9 percent of France's total imports.

West Germany -- Oil supplies would not be immediately endangered if deliveries from Iran dry up, the Economics Ministry in Bonn said.

Iran is West Germany's biggest supplier and provides 18.4 percent of its total oil imports. But a ministry spokesman said there was enough oil currently available on the free market to fill the gap.