Emergency workers battled on Sunday to contain an oil spill near a joint Kuwaiti-Saudi oilfield in the Gulf.

No official reports were available on the source or size of the leak in the waters off Kuwait's southern coast, near the joint Kuwaiti-Saudi offshore Al-Khafji oilfield.

"Emergency oil teams are still struggling to put an oil spill near Kuwait's southern Ras Al-Zour area under control," said Kuwait Petroleum Corporation spokesman Talal al-Khaled in a statement carried by the official KUNA news agency.

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Kuwaiti media quoted local oil experts as saying the spill originated from an old 50-km pipeline from Al-Khafji.

They estimated as many as 35,000 barrels of crude oil may have leaked into the waters off Al-Zour, where Kuwait is building a massive $30bn oil complex that includes a 615,000-barrel-per-day refinery.

Saudi Arabia and Bahrain, located south of Kuwait along the Gulf coast, said the spill had not reached their waters.

Saudi Arabia put into action a "crisis management plan" and was conducting an aerial survey of its oil plants along the coast, said a statement published by the official SPA news agency .

The Kuwait Petroleum Corporation said teams from Saudi Arabian Chevron and Oil Spill Response Limited were cleaning the coastal waters.

Kuwait is a major producer of oil and gas, which make up about 95 percent of its export revenues.