She was responding to an inquiry regarding China’s survey vessel Haiyang Dizhi 4 entering Vietnam’s Exclusive Economic Zone (EEZ) last month.

"All surveillance and scientific research activities on Vietnamese sea areas in accordance with the 1982 United Nations Convention on the Law of the Sea (UNCLOS) must be allowed by Vietnam as stated by the convention.

"Respecting the sovereignty, sovereignty rights and jurisdiction rights of countries and UNCLOS regulations has important meaning for the maintenance of peace, stability, security, cooperation and development on the East Sea, the region and the world," she said.

The East Sea is known internationally as the South China Sea.

Filipino news website Benar News reported on June 16, using two separate vessel-tracking tools, that China’s survey ship Haiyang Dizhi 4 entered Vietnam’s EEZ from June 14-16. It was detected within 200 nautical miles off Vietnam’s coast and roughly 182 nautical miles from Vietnam’s Phu Quy Island, the paper said.

In April, Reuters also reported that Chinese survey vessel Haiyang Dizhi 8, used for offshore seismic surveys, had appeared at 158 km (98 miles) off Vietnam’s coast, within Vietnam’s EEZ.

It was the same vessel that had violated Vietnam’s EEZ and the continental shelf of Vietnam near the Vanguard Bank, occupying the area for many weeks last year.

At the Thursday press meet, Hang also said Vietnam has sent a diplomatic note to protest China's performing military exercises near Paracel Islands this week.

Vietnam has repeatedly condemned China’s illegal actions in the East Sea, asserting it has full legal basis and historical evidence to affirm its sovereignty over the Truong Sa (Spratly) and Huong Sa (Paracel) Islands in accordance with international law. It has also stressed that all activities conducted by any party near either island without prior consent from Vietnam hold no value.