* Engie CEO wrote to AMF regulator earlier in December
* Media reports about tensions in Engie boardroom
PARIS, Dec 22 (Reuters) - The chief executive of French energy group Engie has sent a complaint to the French financial markets regulator warning of attempts to undermine the company, an Engie spokesman said on Thursday.
The spokesman confirmed a story in French weekly magazine Paris Match that Engie chief executive Isabelle Kocher had sent a letter to the AMF regulator on Dec. 19 following several media reports about disagreements between top management.
The Engie spokesman did not give any further details on the matter, while officials at the AMF were not immediately available to comment.
The complaint said the media stories targeted Kocher and were likely to have influenced the company's shares.
"I'm not paranoid, but not naive either," Paris Match quoted Kocher as saying.
Engie's shares have tumbled some 25 percent since the start of the year, underperforming the European utilities index which has fallen 10 percent during the same period.
Engie has also underperformed France's blue-chip CAC-40 index, which is up 4 percent so far in 2016.
Some of the media reports said Kocher was in an untenable situation given the fall in Engie's share price, and difficulties in implementing the group's restructuring plan.
Others media reports said former Engie CEO and current board chairman Gerard Mestrallet, from whom Kocher took over as CEO, was considering replacing her.
Mestrallet said on Nov. 29 that he continued to back Kocher after media reports about tensions between them.
Engie's 2016-18 turnaround strategy includes 15 billion euros ($15.72 billion) worth of asset sales - of which 41 percent have already been signed - and 22 billion euros of investments, as well as cost savings aimed to have a net cumulative impact of 1 billion euros on core earnings by 2018.
$1 = 0.9544 euros Reporting by Gwénaëlle Barzic and Bate Felix; Editing by Sudip Kar-Gupta