Chinese authorities on Sunday denied that an American energy giant has again spilled oil into the waters off North China, rebutting local fishers' claim that a spill is being covered up.

Fishers found large oil slicks near Shandong Province Tuesday, following strong winds the night before, Wang Zhongguo, a fisher from Changdao county, told the Global Times. He said abandoned oil-absorbing pads stained with oil were also found in nearby villages.

Wang said fishers in his village saw a ship towing oil-absorbing pads sail toward the coast of Tuoji Island to avoid heavy winds on March 20.

They identified it as a ship from ConocoPhillips, an energy firm headquartered in America that in 2011 caused two oil spills in the Bohai Sea, which contains several important oil reserves.

The firm restarted its oil field operations in February.

The North China Sea Branch of the State Oceanic Administration denied that a new oil spill occurred around Bohai Sea, claiming that samples it collected from the waterways near Changdao county were found to be fuel oil, except for one sample of crude oil that was not from the Bohai oil field.

ConocoPhillips China released a statement saying that it didn't conduct cleanup exercises at sea on March 20 and its oil fields had no spills.

Jia Fangyi, an attorney representing fishers in Shandong who are trying to obtain compensation from ConocoPhillips for the previous two oil spills, told the Global Times that the oil slicks spotted near Tuoji Island were crude oil, not fuel oil, contrary to the authorities' test results.

"Fishers found their fishing nets and some oil-absorbing pads stained with oil," said Jia. "Large stains made of fine particles of oil were spotted on the shore. Dead, blackened fish were found in the water. It's not fuel oil, which just floats on the sea surface."

Jia said local authorities were burning the oil spill Friday, apparently eliminating evidence. He said that local fishers had to maintain a very low profile while collecting oil slick evidence because of the local government's intention to downplay the issue. Local authorities offered no comment Sunday.

Five hundred fishers in Shandong Province filed a lawsuit against the American company in a district court in Houston, Texas, in July 2012.

After the spills, ConocoPhillips came to an agreement with the Ministry of Agriculture to pay about 1 billion yuan ($160 million) to cover losses of fishermen affected by the spills. However, fishers from Shandong Province were not covered.