ConocoPhillips said Friday it has discovered new oil seeps in an area of China's Bohai Bay where it faces a deadline to clean up spills from earlier this summer.
Of 16 seeps found in the Penglai 19-3 oilfield, each about the size of a small coin, only two were still visible and known to be sometimes active, the company said in a statement.
It said about 1 to 2 liters (a quarter to a half-gallon) of oil and drilling mud were being released each day, but that they are remnants from a spill on June 17 that are shifting from a lower layer of sand to the sea bed.
"The material is viscous and most of it tends to stay on the sea bed," the company said.
ConocoPhillips China, which holds a 49 percent stake in the oilfield and operates its wells in a venture with China's state-owned CNOOC, says it is entirely containing and cleaning up any seeps.
Chinese maritime authorities have threatened to sue the company if it does not meet an Aug. 31 deadline for completing the cleanup and ending risks of new seeps.
Houston, Texas-based ConocoPhillips has said it expects to finish the cleanup by then. But the company has drawn heavy criticism from the State Oceanic Administration, environmental groups and China's state-controlled media for the accident.
"Any company that causes harm to the marine environment must pay all the costs," the Communist Party newspaper People's Daily said in a report Friday summarizing comments by the Oceanic Administration's director, Liu Cigui.
Failure to meet the deadline for cleanup would result in "even more severe measures" being taken according to law, Liu said.
Earlier this week, CNOOC acknowledged its own responsibility and apologized for the spills, which the government estimates have affected 5,500 square kilometers (2,124 square miles) of the Bohai, an important fisheries region.
The State Oceanic Administration reported Friday that the most recent patrols of the beaches in three provinces surrounding Bohai had found no fresh signs of oil contamination from the spills.