June 4

Leaking oil is detected near Platform B of Penglai 19-3 oilfield in northern Bohai Bay.

June 8

The source is found on the seabed in Penglai 19-3.

June 12

The State Oceanic Administration's north sea branch confirms the source of the leak.

June 17

That branch receives a report from ConocoPhillips of a second spill, near Platform C.

June 21

An unidentified person discloses information about the oil spills, and micro bloggers spread it widely.

June 30

Southern Weekly newspaper confirms and reports the spills.

July 5

The State Oceanic Administration gives its first briefing on the spills. Eleven environmental protection organizations send an open letter to ConocoPhillips China, demanding a public apology for the spills and for the company's attempts to conceal them for almost a month.

July 6

The company says the main spill has been contained and the cleanup is nearly finished.

July 13

The administration strongly criticizes the company as being ineffective in containing the leak - which has contaminated at least 4,240 square kilometers - and orders the company to halt production in the affected areas.

July 14

ConocoPhillips estimates the oil spilled into Bohai Bay will reach 1,500 barrels.

July 19

Particles and patches of oil are found along the coasts of northern Hebei and Liaoning provinces. The State Oceanic Administration's north sea branch confirms they are from Penglai 19-3.

July 28

The administration confirms that a sheen of oil from Penglai 19-3 has reached parts of the Shandong province coast.

July 29

The administration tells ConocoPhillips it has until Aug 31 to stop the leaks, clean up the polluted areas and complete a thorough investigation to prevent further spills.

Aug 3

ConocoPillips China finds more oil-based drilling mud near a rig.

Aug 7

The company misses an Aug 7 deadline to clean up all oil-contaminated mud from the seabed near Platform C. The administration urges the company to apologize. On the same day, ConocoPhillips reports two new leaks near Platform B.

Aug 12

The company says the spill volume exceeds 3,200 barrels and concedes it has not done enough to check for potential leaks.

Aug 16

The administration says it will sue ConocoPhillips China for ecological compensation.

Aug 19

A joint investigation team by seven ministries is formed to probe the spills. ConocoPhillips makes its first public apology since the spill started.

Aug 20

The company reports oil is leaking at nine points near Platform C.

Aug 23

The administration says 5,500 sq km of seawater in Bohai Bay have been polluted, with 870 sq km severely contaminated.

Aug 24

ConocoPhillips says all the leaks have been permanently plugged and it is well on track to meet the cleanup deadline.

Aug 25

The State Oceanic Administration says it found 16 leaks near Platform C.

Aug 29

ConocoPhillips says it has cleaned up 99 percent of oil-based drilling mud.

Aug 31

ConocoPhillips says it has sealed all leaks and will take precautions to avert further spills.

Sept. 7

The State Council warned of serious environmental problems in Bohai Bay after a meeting on the handling of the oil spill.