Experts have rejected a recently published Vietnamese book that claims Vietnam's sovereignty over the Nansha and Xisha islands in the South China Sea.

In the 400-page book titled Mark in the East Sea, the author Tran Cong Truc, former chairman of the Vietnamese government's Committee for Boundaries, claimed that Vietnam established and exercised sovereignty over the Nansha and Xisha islands in the 17th century, Vietnam's People's Army Newspaper reported.

The book also claimed that Vietnam was "the first country in the world to possess" the Xisha and Nansha islands, the Hanoi-based Viet Nam News reported.

However, Truc's claim was rejected by Li Guoqiang, deputy director with the Research Center for Chinese Borderland History and Geography at the Chinese Academy of Social Sciences.

"China has indisputable sovereignty over the Xisha and Nansha islands because China discovered and named the area 2,000 years ago, which is much earlier than Vietnam," Li said.

China's fishing and voyaging in the area started as early as in the Qin Dynasty (221BC-206BC), and China started to have jurisdiction over the islands at least in the Tang Dynasty (618-907), according to Li.

He also pointed out that the islands that many Vietnamese history books claimed Vietnam discovered in the 17th century were actually not the Xisha and Nansha islands, but other islands and shoals near the coastal area of Vietnam.

In fact, the Vietnam government admitted China's sovereignty over the Xisha and Nansha islands between the 1950s and 1970s, and Vietnam's then prime minister Pham Van Dong even recognized China's sovereignty over the area in an official letter in 1958 to the then Chinese premier Zhou Enlai, Li told the Global Times.

Zhuang Guotu, dean of the School for Southeast Asian Studies at Xiamen University, told the Global Times that Vietnam made repeated claims over the sovereignty of Xisha and Nansha islands because of the enormous economic benefits in the area, as well as the important geographic location of the area in international shipping.

By 2008, Vietnam had harvested more than 100 million tons of oil and 1.5 trillion cubic meters of natural gas in waters off the Nansha Islands, China Economic Weekly reported.