China's defence ministry said Thursday that Chinese and US officials agreed earlier this month to quicken the pace of efforts to build mutual confidence between their militaries, just weeks after an air confrontation had raised tensions.

US National Security Advisor Susan Rice and General Fan Changlong, vice chairman of the Chinese Communist Party's Central Military Commission, met in early September when Rice visited Beijing for three days of talks with officials including President Xi Jinping.

Chinese defence ministry spokesman Geng Yansheng said that at the meeting Fan and Rice agreed on the importance of a pair of confidence-building measures that the two sides were working towards.

"The two sides agreed that the two confidence building mechanisms were very important for enhancing strategic and mutual trust of the two countries and that relevant work should be conducted at a faster pace so that substantial progress can be made," Geng told a monthly ministry press conference.

"Currently both sides are making joint efforts toward this goal," he added.

The measures have their roots in a summit meeting between Xi and US President Barack Obama in June of 2013 where they agreed to establish a mutual mechanism for identifying major military activities as well as rules of behaviour in the air and at sea, Geng said.

Rice's September visit came three weeks after the Pentagon said in August that an armed Chinese warplane came within 30 feet (nine metres) of a US surveillance aircraft flying over international waters about 135 miles (220 kilometres) east of China's Hainan island.

Beijing, which says that the waters are part of its exclusive economic zone, dismissed the accusation as "groundless" and called on the US to end air and naval surveillance near its borders.

The encounter led to comparisons with an incident in April 2001, when a Chinese fighter jet collided with a US Navy EP-3 spy plane around 110 kilometres off Hainan.

One Chinese pilot died and the US plane had to make an emergency landing on Hainan where China detained the 24-member crew for more than a week until Beijing and Washington cut a deal for their release.

Geng made no mention of the incident at the press conference.

The United States is focusing greater attention on Asia and has boosted its military presence in the region, a move that has alarmed China and emboldened its rivals.

China, meanwhile, has been rapidly modernising its military amid maritime territorial disputes with regional neighbours such as Japan, Vietnam and the Philippines.

Separately, Geng announced that the two sides will hold their 15th round of defence consultative talks in the middle of October in Washington.

During those talks the strategic planning departments of the respective militaries will hold their first ever dialogue, he added.