The marine ecosystems of northeast China's coastal waters near the area heavily-polluted by a major oil spill appear to be unaffected by the slick, a senior Chinese oceanologist told Xinhua Monday.

Wang Fan, head of a marine environment investigation organized by the Chinese Academy of Sciences Institute of Oceanology, said, "So far we've found nothing unusual from the marine ecosystem parameters in that area."

The investigation, conducted from July 25 to 29, collected data from nine offshore observation stations, covering areas up to 30 nautical miles off the coast, including the 10 square kilometers of heavily polluted seas near Xingang, Dalian, where pipeline explosions caused the spill on July 16.

In the heavily-polluted area, the oil on the sea surface was up to 30 centimeters deep before the clean-up began.

A group of 19 scientists and technicians involved in oceanography, marine geology, marine ecosystems, halobiotic sciences and marine chemistry were participating in the investigation.

The data was still being analyzed and a detailed report, which would include ecosystem conditions in the heavily-polluted area, would come out later this week, Wang said.

"The report can help the local government take further steps and bail out enterprises in related industries such as fisheries," Wang said.

"But the findings will only show the current situation in the area," Wang said. "We need to continue our research in the following weeks to better reflect ecological developments in the spill area."

Dalian Vice Mayor Dai Yulin said on July 26 that workers had contained the oil slick, stopping it from reaching international waters.

The government has mobilized 8,150 fishing boats, 266 oil-skimming vessels, biological cleaning agents and volunteers to reduce the environmental impact of the spill.

Maritime agencies and oil companies had laid down more than 40,000 meters of oil barriers and 65 tonnes of oil absorbent mats, Dai said.

The pollution source had been brought under control, and most of the spilt oil had been mopped up, Dai said.

The explosion caused the spill at a storage depot in the Dalian Xingang Harbor when it hit an oil pipeline from a Libyan oil tanker as it was uploading, triggering an adjacent smaller pipeline to explode.