The Russian securities watchdog says it is abandoning its efforts to change Norilsk Nickel's plans for restructuring.

The Federal Financial Markets Service (FFMS) said that it had decided to drop the campaign after years of expenditure.

The FFMS was seeking to overturn the firm's purchase of London-based metals trading company Norimet, which took place four years ago as part of a wider programme of restructuring.

However, in a statement a FFMS spokesman told Reuters it was "no longer interested in pursuing this case".

The watchdog questioned the legality of the Norimet purchase, which Norilsk has staunchly defended and which was also rejected by the country's Supreme Arbitration Court in April 2002.

New hearings took place this week as part of an appeal against the ruling but rejection from the court prompted the watchdog to drop the case.