China plans to establish a fund to support troubled trust firms as repayment risks accumulate in the 13 trillion yuan ($2.1 trillion) industry.

Under rules jointly issued by the China Banking Regulatory Commission and the Ministry of Finance, each trust firm is required to contribute 1 percent of their net assets to the fund, while each trust product will pay 1 percent of the money raised, according to a statement on Friday.

Premier Li Keqiang is trying to sustain economic growth while containing financial stress after the nation's shadow-banking system started swelling in 2010. Trusts, a high-yield investment, grew in the third quarter at the slowest pace since that year as regulators imposed a stricter approval process on new products and investors grew more wary of defaults.

The protection fund will be used to help trust firms that are restructured because of insolvency or that are going bankrupt, firms that have shut because of illegal operations, and those with short-term liquidity difficulties, according to the statement.

After being bailed out by the fund, trust companies' original shareholders and senior executives will be held "accountable based on law and regulation," according to the statement. The fund can also invest in bank deposits, interbank lending, government bonds, central bank bills and money-market funds.

China had 68 trust firms with shareholders' equity totaling 288 billion yuan at the end of September, according to the statement. About 69 percent of trust assets were used to help finance the economy, including the real estate, mining, energy and infrastructure sectors.