HANOI • Vietnam has accused China of making "erroneous statements" in the latest round of an escalating diplomatic spat over flights to a disputed reef in the Spratly islands in the South China Sea, which is claimed by both countries.

China has conducted several flights this year through Vietnamese airspace to a newly built runway on the Fiery Cross Reef in the Spratly islands, leading Hanoi to accuse Beijing of threatening regional safety with the "unannounced" flights. But Beijing argues that it has the right to conduct "state aviation activities".

Hanoi fired off the latest barb late on Tuesday in the increasingly bitter diplomatic spat, saying Beijing was making "erroneous statements" by claiming it had informed Vietnamese air traffic control about the flights.

"Ho Chi Minh... Control Centre did not receive any notification by China of the flight plans," Foreign Ministry spokesman Le Hai Binh said in a statement. The flights, he added, were "aimed at asserting (China's) illegal sovereignty claims over the Trong Sa archipelago", referring to the Spratlys by their Vietnamese name.

He also said the flights to Fiery Cross Reef, under any name, affected aviation security, safety and freedom in the area.

This year alone, Vietnam has logged at least 46 incidents of Chinese planes flying without warning through airspace monitored by air traffic control in the southern metropolis of Ho Chi Minh City, according to the authorities cited by local media. State media also reported that Vietnam sent a protest letter about the flights to China, as well as the International Civil Aviation Organisation.

Beijing began work in 2014 on a 3km runway on Fiery Cross Reef, which is also known as Yongshu, about 1,000km from China's island province of Hainan. The runway is one of three that China has built in the Spratlys in the past year.

The Philippines recently filed a diplomatic protest over China's test flights at the Fiery Cross Reef, which it referred to as the Kagitingan Reef. The protest submitted by its Department of Foreign Affairs on Jan 8 was over test flights conducted by China to the Kagitingan which Manila viewed as being provocative and "restricting the freedom of navigation and overflight in the West Philippine Sea", according to department spokesman Charles Jose, the Philippine Enquirer reported.

Mr Jose was quoted as saying that "these actions by China have elevated tensions and anxiety in the region and are in violation of the spirit and letter of the Asean-China Declaration on the Conduct of Parties". The declaration was signed between the regional group and Beijing in 2002.

China's claim to almost all of the South China Sea puts it at odds with regional neighbours, the Philippines, Vietnam, Malaysia, Brunei and Taiwan, which also stake partial claims.

AGENCE FRANCE-PRESSE.