DHAHRAN, SAUDI ARABIA, JAN. 30 -- The chief of the U.S. team dispatched by President Bush to help fight the massive Persian Gulf oil slick said today that certain wind conditions could produce a "very high risk" that the spill would penetrate Saudi protective barriers and contaminate key water purification plants.

The comments by Coast Guard Capt. Donald Jensen, who helped oversee the cleanup of the 1989 Exxon Valdez oil spill in Alaska, aggravated fears here. As the 50-mile-long slick has floated southward from Kuwait, Saudi officials have said their coastal desalination plants were well protected by rows of plastic booms strung across the intake points to block entry of crude oil.

But after flying over the southern portion of the spill on Monday, Jensen said the slick is so huge that it could "inundate" the facilities if strong winds push the oil onto the coast.

"That's a possibility," said Jensen, when asked by reporters if the water plants will be contaminated. "If the full onslaught hits . . . there's no way {the boom} is going to protect it." According to the U.S. Coast Guard, however, prevailing winds are northwesterly at this time of year and would tend to keep the oil off the Saudi coast.

Another danger, Jensen said, is that the slick will break up, forming globs of heavy "tar balls" that will sink and then be swept by currents into the plants' filters. "It takes a small quantity of oil to foul up those filters," he said.

Closure of the plants would have a severe impact on this country of 15 million people, according to environmental and health experts here. The eastern portion of Saudi Arabia has only negligible amounts of drinkable groundwater, depending almost entirely on desalination plants fed by the Persian Gulf.

The most critical and immedately threatened of the plants is in the industrial city of Jubail. About 100 miles south of the Kuwaiti border, the facility supplies water for large portions of northeastern Saudi Arabia, including the capital city of Riyadh.

Abdullah Dabbagh, director of the Research Institute of King Fahd University of Petroleum and Minerals, said computer projections show the southern portion of the slick is now only two to three days from the Jubail area. He cited Saudi estimates that the slick contains about 7 million barrels of oil. It remains a few miles off the Saudi coastline but if easterly winds blow the oil to the coast, "it will cover Jubail totally," said Dabbagh.

"Everybody is very worried, no doubt about it," said Dabbagh, who is advising the Saudi team that is fighting the slick. "We don't know what will happen with this huge big monster. That's the problem. Nobody has ever had any experience with anything like this."

Saudi officials continued to reassure the public that there is no reason for concern. Nisar Tawfig, vice president of the Saudi Meteorological and Environmental Protection Administration, said at a news conference, "There isn't an immediate threat" to the desalination plant at Jubail or nearby industrial facilities that use sea water as coolant.

Despite those assurances, there have been reports of panic buying of bottled water in Jubail in recent days. In addition, sources say, the government has made contingency plans to use the small amounts of water available from wells.

Blaming the new slick on Iraqi President Saddam Hussein's decision to dump oil into the Persian Gulf, Tawfig said, "All of us are appalled that anyone -- let alone a leader of an Islamic nation -- would have such disregard for his God-given responsibilities" to preserve the environment.

News services added:

A separate, smaller slick recently was detected in the gulf, emanating from an Iraqi oil terminal, according to British sources quoted by the British Broadcasting Corp. The allied military commander threatened to bomb that site just as was done Sunday to curb the oil flow from the Sea Island terminal in Kuwait.

Gen. H. Norman Schwarzkopf, commander of allied forces, said oil has been leaking for several days from an offshore platform at Mina al-Baqr off the Iraqi coast. "We're watching that oil spill and if it gets out of control, we'll do it again," he said.

Air Force Capt. Barclay Trehal said after a photo reconnaissance mission along the coast that crude was "being spread from various sources" in Iraq and Kuwait.