* Takeover panel says rebels not acting together
* Peter Hambro calls on shareholders to support existing board
* Says rival proposals would disrupt 'positive projects'
LONDON, June 15 (Reuters) - There is no legal requirement for a formal takeover bid for Russian-focused gold miner Petropavlovsk and three out of four board nominees put forward by rebel shareholders are independent, Britain's Takeover Panel said on Thursday.
The watchdog assessed resolutions from shareholders seeking to overhaul the Petropavlovsk board at its annual meeting next week and sought to determine whether they were acting in concert.
Peter Hambro, who has headed Petropavlovsk since he founded it in 1994, questioned whether the shareholders seeking change were acting together to pursue "a takeover by stealth", avoiding paying the premium a formal takeover would require.
The Takeover Panel found the rebel shareholders' resolutions were not "board control-seeking", the shareholders were not acting together and therefore there was no requirement for a mandatory offer.
Hambro told Reuters he accepted "the narrow remit" of the Takeover Panel, but urged shareholders attending the company's annual meeting next Thursday to oppose the rebels' proposals, which include blocking his re-appointment to the board.
The changes "would be disruptive to the successful completion of the very promising projects we have under way," he said.
Hambro has stepped down as chairman but is an executive director and says the company is on track after returning to profit in 2016.
Citing inadequate governance, the dissident shareholders, which include conglomerate Renova, Sothic Capital Management and M&G, who between them hold more than 30 percent of Petropavlovsk, have proposed Ian Ashby as chairman.
Ashby was named in May as a non-executive director at Anglo American.
In addition the rebels have nominated Vladislav Egorov, who works for the Renova group, Garrett Soden, who has worked for the Lundin group of companies for a decade, and Bruce Buck, chairman of Chelsea Football Club.
The Takeover Panel said all of the proposed directors were independent, with the exception of Egorov, who it said "is not considered to be independent, owing to his employment by Renova". Renova declined to comment.
In the years before a restructuring in 2015, Petropavlovsk's equity value collapsed.
The share price has recovered from lows around 2 pence at the end of 2014 to just over 8 pence, boosted by its return to profit last year, but the rebel shareholders say it is still underperforming its peers. (Reporting by Barbara Lewis and Carolyn Cohn; additional reporting by Polina Devitt in Moscow; Editing by Keith Weir)