The jailing of another Australian in murky circumstances has raised new questions about the risks of doing business in China, just as Prime Minister Julia Gillard prepares to lead a high-powered delegation to a Chinese business forum.

Carl Mather was quietly convicted of assault in January after attempting to resist four people who barged into his Chinese apartment, while he carried his three-year-old daughter in his arms.

Another Aussie in trouble: Carl Mather with wife Xie Qun and daughter Doreen.

The 54-year-old Australian English teacher opened the door of his Nanjing apartment to a man he knew, Gao Long, but three others sprang from hiding places and forced their way in.

They were demanding to see his wife, Xie Qun, in a language he couldn't understand, and he feared they would abduct their daughter for leverage in an ongoing dispute over money and pride.