This satellite image shows the Yongshu Jiao of China's Nansha Islands. [Photo/Xinhua]

BEIJING - A test flight to a newly-built airfield on a South China Sea reef was a matter "completely within China's sovereignty," a Foreign Ministry spokesperson said late Saturday evening.

Spokeswoman Hua Chunying said China has finished building an airfield on Yongshu Jiao of China's Nansha Islands.

The Chinese government used a civil aircraft to conduct the flight in order to test whether the airfield facilities meet civil aviation standards, she said, in response to reported objections of Vietnam's foreign ministry.

"China has indisputable sovereignty over the Nansha Islands and their adjacent waters. China will not accept the unfounded accusation from the Vietnamese side," Hua said.

At present, the relations between China and Vietnam maintain a momentum of development. China hopes Vietnam can work accordingly to achieve "sustainable, healthy and stable" development of bilateral ties, Hua said.