LONDON – Russian gold miner Petropavlovsk has asked British regulators to investigate the identity of shareholders pressing for an overhaul of the board only a year after a previous revolt forced change, sources close to the company said.

The London-listed firm, which has underperformed peers for about a decade, is near the end of a quest to bring on technology to boost profits from the treatment of refractory gold ore, which is very hard to process using traditional methods.

It says fresh management upheaval would set back progress just when its fortunes could be about to be transformed.

"Petropavlovsk has raised the mystery shareholder issue with the (UK Takeover) Panel and the UK Listing Authority," (UKLA) one of the sources said, asking not to be named.

The source added the company had asked the regulators to investigate and take appropriate action, without elaborating.

A spokesman for the Financial Conduct Authority, of which the UKLA is part, declined to comment. A spokesman for the Takeover Panel had no immediate comment.

Investors under the names of CABS Platform and Slevin have called for long-time chief executive and co-founder Pavel Maslovskiy to return to the board and for other management changes.

Together the two entities own just over 9% of Petropavlovsk's stock. They have offshore addresses in Panama and Anguilla, according to Thomson Reuters data, and have not responded to attempts to contact them.

Maslovskiy told Reuters they were not connected to him.

The company's biggest shareholder, Kazakh entrepreneur Kenges Rakishev, also says he is not connected to them, although he has said he largely backs their demands.

Maslovskiy resigned last year after the company's co-founder Peter Hambro was ousted by a shareholder revolt. Hambro says he is not expecting to return, while Maslovskiy says he would be willing to do so.

Gertjan Koomen, managing partner at Sothic Capital Management, voted for last year's board changes on the grounds of poor governance.

He said the company was now on track, disagreed with the new activist demands to bring back three former directors and thought the current CEO should keep his office, but he would not oppose the return of Maslovskiy as a non-executive director.

"In this way the company can benefit from his operational experience," he said.

Koomen said he agreed regulators should investigate to determine the identity of the activist shareholders.