Flinders Mines shareholders will have to wait even longer to wrap up a $558 million takeover after a minority shareholder in suitor Magnitorosk Iron and Steel (MMK) launched legal action to stop the bid from proceeding.

Reports suggest the applicant holds less than 0.001 per cent of the Russian steelmaker MMK but has asked the Russian courts to intervene on fears that the takeover will cause unacceptable financial and operational risks.