LONDON, July 7 (Xinhua) -- New rules aimed at forcing London hedge funds to disclose short positions in companies holding rights issues have caused confusion, the Financial Times reported Monday.

    About half the disclosures made by hedge funds contained errors "as the funds struggle to get to grips with complex calculations," the front-page report on the paper said.

    It said 20 of the 41 disclosures have missed filing deadlines, contained the wrong calculations or were not even required.

    The errors demonstrated the difficulties faced by hedge funds and other short-sellers in applying rules for which they were given just a week's notice by the Financial Services Authority (FSA).

    The FSA used its emergency powers for the first time in June to bring in regulations requiring the publication by 3.30 p.m. the next day of a short position of 0.25 percent or more, or of a company going through a rights issue.