Toxic oil spilled from a Liberian-flagged cargo ship stuck on a reef off New Zealand began washing ashore around the port city of Tauranga Monday as a union alleged the vessel had multiple problems before it left its last port.

Toxic oil spilled from a Liberian-flagged cargo ship stuck on a reef off New Zealand began washing ashore around the port city of Taurangaon, October 10, 2011, New Zealand. [Xinhua]

Maritime New Zealand (MNZ), the country's shipping authority, warned the public to stay out of the sea and to avoid touching the oil and eating seafood in affected areas along the east of the North Island.

A fuel tanker had begun taking fuel of the 47,000-tonne Rena, which grounded early Wednesday on the Astrolabe Reef, about 12 nautical miles offshore, near Tauranga, said MNZ.

However, oil had washed ashore in Tauranga "in individual clumps of about fist-sized patties about 5 mm high and stranded on the tide line about every 700 to 800 mm apart," said an MNZ statement.

"People should not touch or attempt to clean up oil as it is toxic," it said.

"A public health warning has been issued. No shellfish or fin fish should be eaten from waters with visible oil contamination."

Public Health officials were erecting signs warning people to stay away from affected beaches and to avoid inhaling fumes from the oil as they could "cause irritation in mouth, nose throat and lungs."

MNZ had a shoreline clean-up assessment team investigating reports of oil washing ashore near Tauranga and Mount Maunganui, one of New Zealand's most popular beach resorts.

More oil was expected to come ashore over the next 24 hours, but the amount was unknown, said the MNZ statement.

Toxic oil spilled from a Liberian-flagged cargo ship stuck on a reef off New Zealand began washing ashore around the port city of Taurangaon, October 10, 2011, New Zealand. [Xinhua]

"One of the tanks containing oil has a platform in it, which means the salvage team have to climb inside the tank and manually place the pumping equipment inside rather than lowering it in. This will take a little longer than planned," it said.

"All vents on the ship are now sealed to prevent oil escaping."

Bad weather had stopped pumping of the oil from the Rena to the bunker barge Awanuia late Sunday, after about 10 tonnes of fuel had been transferred.

The weather was expected to deteriorate further Monday with the moderate seas turning rough and showers reducing visibility.