Six of the 11 Chinese companies listed in Singapore that sold convertible bonds between 2005 and 2008 have said they are unable to repay debts, the South China Morning Post reported, citing an investor association official.

The Securities Investors Association of Singapore asked the Chinese government to discipline the companies since Singapore doesn’t have the authority to do so, Chairman David Gerald said, according to the Hong Kong-based newspaper. The association represents 4,000 small shareholders, the report said.