Foreign Ministry spokeswoman Le Thi Thu Hang reiterated Thursday that Vietnam has full historical and legal basis to assert its sovereignty over the Paracel (Hoang Sa) and Spratly (Truong Sa) Islands in accordance with international law.

The South China Sea is known in Vietnam as the East Sea.

"The fact that China is educating its future generations with information that is contrary to historical facts and international law is not beneficial to the friendship (between Vietnam and China)," she added.

Chinese newspaper Global Times reported on August 1 that China would publish new history textbooks for high school students starting next month, in which they say the South China Sea and the Senkaku Islands, currently under Japan’s control, on the East China Sea have been part of Chinese territory since ancient times.

China had earlier stirred up controversy and attracted criticism over its "nine-dash line" to claim sovereignty over almost all of the South China Sea, saying it has "historical rights" to the waters within the line. But a 2016 ruling by the Permanent Court of Arbitration denied China’s claims.

Southeast Asia expert Bill Hayton has pointed out that nine-dash line is a relatively new claim based on a line drawn around nonexistent islands on a bad copy of a British-drawn map in 1936.

This originated from China's own ignorance and seriously mistaken information on the sea's islands in the 1930s, Hayton said at the ninth annual South China Sea Conference hosted by the Center for Strategic and International Studies (CSIS) in Washington last month.

China claims almost the entire South China Sea, including waters close to Taiwan and Southeast Asian countries Brunei, Indonesia, Malaysia, the Philippines and Vietnam.