New air-to-air missiles previously had to take eight tests where they hit a moving target to prove their worth, a requirement that has now risen to 15.

When other tests - for example, checking its resilience against electromagnetic pulse attacks - are factored in, the new missile will have to undertake around 20 tests.

In recent years China has increased the frequency and scale of military exercises using live, cutting-edge weapons.

• EXPLAINER: China joins heated race for new missiles

"Some problems such as unsatisfactory equipment delivery and unstable quality have surfaced," military researcher Li Gencheng and colleagues with the China Airborne Missile Academy in Luoyang wrote in a paper published in the domestic journal Aero Weaponry in August.

"The high command wanted these problems solving before mass production," he added.

Most missile tests in China are conducted in secrecy, but some can be detected by satellites. Earlier this month, Ned Price, a spokesman for the US Department of State, said China had launched at least 250 ballistic missiles between January and September, equivalent to the total number of tests last year.

Price did not reveal the number of tests by the US in the same period, but he said that the White House interpreted the Chinese tests as a "rapid expansion of the PRC's nuclear capabilities," adding it was "especially concerning".

Chinese state media said the sources for Price's figures were dubious and the foreign ministry insisted that China did not want a nuclear arms race.

According to Li and colleagues, increasing missile test flights is not an easy decision to make because of the cost involved.

Watch more in iWantv or TFC.tv

The Chinese military initially came up with two proposals. One required a new missile to be fired 15 times without any failure, the other 27 times with no more than one failure to ensure a success rate of more than 90 per cent.

The military's proposals prompted protests from defense contractors, who argued new missiles' chances of passing these tests would be less than 20 per cent.

After negotiations, the People's Liberation Army and state-owned defense companies reached a compromise, according to Li, in which the contractor produces 50 missiles, from which the military randomly picks 15 for testing.

The new weapon gets the green light for deployment if no more than two miss the target.

• China surprises US with hypersonic missile test, FT reports

Limiting the number of missile tests is an important aspect of international arms control treaties because the more reliable a weapon is proved to be, the more confidence governments have in using it.

Other countries have also experienced problems when testing missiles. For example, in May this year a US Minuteman III intercontinental ballistic missile failed to take off in a test flight. In 2018, the US military had to press the self-destruct button on another Minuteman after it developed "anomalies" during a test over the Pacific.

According to a separate study, the Chinese military is facing an increasing number of quality control problems when developing new weapons.

In the past, missiles would be tested in different environments - such as deserts or islands - for extended periods, but it is not possible to do this with the large number of new weapons that have appeared in recent years, according to senior engineer Liu Yan and her colleagues at the Beijing Institute of Electronic System Engineers in a paper published in the journal Modern Defense Technology in August.

The PLA therefore established a new, centralized task force to oversee the reliability of new missiles, built a number of testing facilities with controlled environments to speed up tests and plans to use artificial intelligence technology, according to the paper.

In a meeting with representatives from the military and defense industry on Tuesday, President Xi Jinping said China's "weapons and equipment construction has achieved leapfrog development and made historic achievements" over the last five years.

He urged the military and industrial leaders to "step up a modern management system while breaking new ground in the manufacturing of weapons and equipment", according to the People's Daily.

Recently it was reported that China had tested two new hypersonic weapons that could travel at more than five times the speed of sound - a development a senior US commander described as "very significant", although Beijing denied that the tests had a military purpose.

Copyright (c) 2021. South China Morning Post Publishers Ltd. All rights reserved.