The strictest ever expenditure and salary cap will be implemented in all levels of professional leagues next season, the Chinese Football Association (CFA) revealed Monday.

In China's top flight, the Chinese Super League (CSL), the pre-tax annual income of an overseas player should be no more than 3 million euros ($3.63 million), while the maximum salary for a domestic player is 5 million yuan ($765,000) per year before tax.

"The policy aims to curb the investment bubbles in our leagues and promote the healthy and sustainable development of professional football," the CFA document read.

For a CSL Club, they may only spend a maximum total of 600 million yuan every year including a 10 million euro expenditure cap for all overseas players at the club. The average annual salary of their domestic players should be below 3 million yuan.

A CFA source told Xinhua that the average annual expenditure for CSL clubs was about 1.1 billion yuan in 2018 season, with the majority of them facing losses.

"The CSL club expenditure is about 10 times higher than South Korea's K-League and three times higher than Japan's J-league. But our national team is lagging far behind. The bubbles not only affect the present of Chinese football, but also hurts its future," said CFA President Chen Xuyuan, noting that the Chinese football governing body has set a series of tough measures to punish violations.

In order to execute the policy effectively, the CFA demanded clubs sign new contracts with all players following the application of salary cap. For those athletes whose previous contract values are above the cap, their clubs could sign supplemental agreements to make up the differences within three years, which will no be included in the clubs' expenditure.