A Chinese helicopter landed on the oil drilling rig Haiyang Shiyou-981 in the East Sea on June 17.

The rig is illegally standing in Vietnam's exclusive economic zone and continental shelf, according to the Vietnam Fisheries Surveillance Department.

China still has 136 ships, including coastguard, cargo and fishing vessels, tugboats, and five military ships surrounding the rig.

The Chinese fleet kept on circling and standing ready to ram Vietnamese vessels, while approaching them to within 30-50m, the department reported.

In addition, Chinese fishing ships escorted by a coastguard ship coded 46102 formed a line to block Vietnamese fishing boats undertaking their normal catching activities about 30 nautical miles from the rig.

Despite strong wind and rough seas, Vietnamese ships tried to get closer to the rig to protest and demand China move it from Vietnam's waters.

At the beginning of May, China illegally dispatched the rig as well as a large fleet of armed vessel.

Despite Vietnam's protests, China has expanded its scale of operation and moved the rig twice since. The latest location is 60 nautical miles inside Vietnam's continental shelf and exclusive economic zone.

China was probably preparing to move oil rig Haiyang Shiyou-981, illegally stationed in Vietnamese waters, to a new position on June 17.

Despite Vietnam's protests, China has expanded its scale of operation and moved the rig to about 60 nautical miles deep inside Vietnam's continental shelf and exclusive economic zone.

VNS/VNN