MANILA, Philippines — Despite the government's earlier declaration of banning foreign marine survey ships in the country's exclusive economic zone, a Chinese research vessel was once again spotted operating in Philippine waters.

Analyst Ryan Martinson, assistant professor at China Maritime Studies Institute, posted on Twitter that Chinese oceanographic ship "Zhang Jian" has returned to the Philippine EEZ.

This is the same Chinese research vessel seen operating 80 nautical miles from the country's east coast from August 3 to 5.

Maritime law expert Jay Batongbacal, director of the University of the Philippines Institute for Maritime Affairs and Law of the Sea, also posted a screenshot from Facebook group Karagatan Patrol showing the track of the Chinese vessel.

The Chinese oceanographic survey ship "Zhangjian" has returned to the Philippines exclusive economic zone. Heading west at 10 knots. https://t.co/nrzykbNUCK pic.twitter.com/kLVQGQekEt — Ryan Martinson (@rdmartinson88) August 21, 2019

The Chinese survey ship appears to have been approximately 200 kilometers northeast of Catanduanes as of August 22, based on the post of Facebook user Jess Floren.

Info from Jess of Karagatan (Sea) Patrol. After hanging out for days outside the PH EEZ, Chinese research vessel quietly crosses and continues it's survey into it, maybe thinking no one's looking. You can almost hear the captain whistling... pic.twitter.com/73cVmk2opE — Jay L Batongbacal (@JayBatongbacal) August 23, 2019

"After hanging out for days outside the PH EEZ, Chinese research vessel quietly corsses and continues its survey into it, maybe thinking no one's looking," Batongbacal tweeted.

Data from ship tracking intelligence MarineTraffic showed that Zhang Jian was off the coast of Samar as of 3:15 a.m on August 23.

Data from ship tracking intelligence MarineTraffic shows Chinese oceanographic survey ship Zhang Jian in the area of Samar on August 23. Data from ship tracking intelligence MarineTraffic shows Chinese oceanographic survey ship Zhang Jian in the area of Samar on August 23.

Philippines warns of 'unfriendly' response to foreign ships without clearance

This latest development came days after the Duterte administration warned that it will enforce an "unfriendly" response against foreign vessels passing through Philippine territorial waters.

“To avoid misunderstanding in the future, the president is putting on notice that beginning today, all foreign vessels passing our territorial waters must notify and get clearance from the proper government authority well in advance of the actual passage,” presidential spokesperson Salvador Panelo said.

Foreign Affair Secretary Teodoro Locsin Jr. had also called for a ban on foreign survey ships entering the country's waters.

"To pick and choose invites suspicion of favoritism. Will universalize the ban. Period. Granting exception to one country will automatically lift ban universally," Locsin said on Twitter earlier this week.