The worst oil spill in the history of the Persian Gulf is threatening to become a major ecological disaster because the warring nations of Iran and Iraq cannot agree on even a partial cease-fire allowing technicians to cap three damaged offshore oil wells.

Other Arab gulf states and western oil companies have been unable to persuade the two enemies to hold their fire long enough to permit the Houston-based Red Adair Oil Well Fire and Blowout Co. to go to Iran's Nowruz oil field to halt the flowing crude.

"Both Iran and Iraq are using it for political purposes," said one diplomat here.

The oil well platforms at the Nowruz field--roughly halfway between Iran's oil terminal on Khark Island and Kuwait--were set afire by missiles fired from Iraqi helicopters March 2. An estimated 5,000 to 7,000 barrels of oil has been spilling from them every day since. In addition, a third nearby well, accidentally hit by a ship in early February, is also leaking.

There is no agreement among specialists in Kuwait and Bahrain how big the slick is, with estimates ranging from 150 to 12,000 square miles. Blown southeast by prevailing winds at roughly three miles a day, the slick of extremely heavy crude oil is nearing the coast of Qatar and Bahrain and patches of it have been sighted farther south near the United Arab Emirates.

"Theoretically, it could cover the whole gulf by the middle of May and all the water could become contaminated," remarked the diplomat.

Nineteen oil companies operating in the gulf issued a statement after a meeting yesterday in Bahrain warning that the entire gulf would soon become "one vast oil lake" if the three damaged wells were not capped immediately.

The statement also said the leakage held "the potential for untold environmental and ecological damage" and that all the available antipollution equipment would not be sufficient to deal with the crisis unless the wells were capped.

Western diplomatic sources here said that even if the wells were capped immediately, "ecologically it is going to do a tremendous amount of damage. Over a period of months this will spread and they gulf Arab states are worried it will affect their water desalination plants."

The Regional Organization for the Protection of the Marine Environment, based here in Kuwait, has been trying to arrange a cease-fire in a gulf-wide effort to combat the pollution. But so far it has been unable to get Iran and Iraq, which are both members, even to attend a joint meeting.

An official of the organization, Abdul Latif Zaiydan, returned here today from talks in Tehran with Iranian officials amid conflicting reports about whether Iran is willing to cooperate with the organization.

On Monday Iranian Prime Minister Hussein Musavi said Iran was not prepared to cooperate with the regional organization any longer. But yesterday the Iranian ambassador to Kuwait, Ali Shams Ardakani delivered a letter to the group calling for the meeting.

Musavi accused Iraq of causing the spillage "in total disregard for the pollution problems this would cause to the Emirates, Bahrain and Kuwait, which financially have not taken any strict stance against Iraq." This appeared to be a reference to these countries' financial support for Iraq's war against Iran.

The Iraqis, for their part, have accused Iran of dragging its feet on paying American companies for the capping operation.

Ardakani, in an interview here, rejected the Iraqi charge and said Iran had already paid $1 million, primarily to the Red Adair company that has $100,000 worth of equipment standing by.

He said the problem was not a technical one but a "political and military issue," charging that the Iraqis had publicly warned they would attack anyone coming close to the damaged wells.

Western diplomats here, and privately some Kuwaiti officials as well, tend to blame Iraq primarily for the stalemate and say neither the regional environmental organization nor the Red Adair company has received the necessary guarantees from Iraq to allow the capping operation to go ahead.

"The Iraqis seem to feel that if the slick blows toward Iranian shores, it's fine," commented one diplomat.

Just why Iraq attacked the offshore oil wells is not clear given the obvious risk of pollution.

But several sources, who asked not to be named, said the Iraqis were trying to get a local cease-fire in and around the Nowruz oil field and then use it as a wedge to obtain a broader one in its 30-month war with Iran. Iran was opposing this, they said.

However, the Iranians, as indicated by the Musavi statement, seem to be also using the crisis in an attempt to drive a wedge between Iraq and its Arab gulf backers who have provided at least $20 billion for the Iraqi war effort.

Meanwhile, the threat to the whole gulf is growing daily with officials on the Arab side most concerned about the threat the slick poses to desalination plants. Kuwait, Qatar and the Emirates are heavily dependent on such plants for their water supply, and Saudi Arabia could also be seriously affected if the slick hits its shores.

The problem is compounded, specialists here and in Bahrain say, by the fact that the oil is of an extremely heavy, tar-like quality and has sunk as much as two feet below the surface in some areas. This makes it difficult to disperse with chemicals and to block or channel with barriers.

An official of Bahrain's Health Ministry's environmental protection department, contacted by phone, said there were no chemicals available in the gulf right now to deal with this kind of crude.

He also said gulf environmental protection officials were having difficulty getting precise information about the slick because pictures taken by planes flying around its southern edge did not match available satellite photographs. The latter, he said, indicated the problem was much worse than photographs taken by aircraft suggested.

An additional problem, he said, was that the slick was breaking up and going in different directions with one piece only five miles from Qatar's shores this morning. Another piece, about 12 miles off Bahrain, was expected to just miss hitting the island Thursday or Friday if the winds continue to blow in their current direction.

"The real problem is what is coming behind it," he said referring to the main body of the slick.