Kuwait City (AFP) - Kuwaiti authorities on Tuesday reported a second oil slick off the Gulf state's shores days after saying another large spill was under control.

The new slick was spotted near the capital, some 60 kilometres (37 miles) north of the first spill, tweeted Sheikh Talal Khaled Al-Sabah, spokesman for national oil conglomerate Kuwait Petroleum Corp (KPC).

Kuwait's Environment Public Authority said the latest spill was about 1.6 kilometres long, adding that measures were being taken to contain it.

Private environmental group Kuwait Green Line said on Tuesday that new oil slicks had been spotted and the spill was spreading.

Last week, a large oil spill hit Kuwait's southern coast near Saudi Arabia and close to the joint Saudi-Kuwaiti offshore oilfield at Al-Khafji.

Oil officials had said emergency workers managed to clean up most of the spill and that the situation was under control.

Precautionary measures were taken around vital installations in Al-Zour area where a huge $30-billion oil complex including a 615,000-barrel-per-day refinery is being built.

The area also has two power and water desalination plants which were declared safe from contamination.

The source of the crude spill has not yet been determined but officials said samples were sent abroad for examination.

Kuwaiti media on Sunday quoted local oil experts as saying the spill came from an old 50-kilometre-long pipeline from Al-Khafji.

The experts estimated that as many as 35,000 barrels of crude may have leaked into the waters off Al-Zour.

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

The KPC said teams from Saudi Arabian Chevron and Oil Spill Response Limited (OSRL) had joined the coastal clean-up operations.

OPEC member Kuwait pumps around 2.7 million barrels per day of crude oil, providing around 85 percent of its public revenues.