* Emirate now holds 16.7 pct of group's voting rights-filing
* CEO controls company thanks to limited partnership structure
* Group to hold AGM on Thursday
By Mathieu Rosemain and Gwénaëlle Barzic
PARIS, May 3 (Reuters) - Qatar has become media group Lagardere's top shareholder in terms of both share capital and voting rights as a result of a French law that favours long-term investors.
Qatar Holding, part of the emirate's sovereign wealth fund, said on Wednesday that its Lagardere voting rights had risen to 16.7 percent, based on a share stake of about 13 percent.
The Gulf state previously held close to 10 percent of the voting rights, while Lagardere's chief executive Arnaud Lagadere held 7.65 percent of its capital and 11.9 percent of voting rights at end of last year, a 2016 registration document showed.
Qatar, which first invested in Lagardere in 2006, has been a staunch supporter of Arnaud Lagardere whose strategy for the company founded by his father has faced criticism from some shareholders.
"The Lagardere group welcomes the trust placed in it by Qatar Holding LLC, known for being a demanding and long-term shareholder," a spokesman for Lagardere said in an email.
France's 2014 "Florange" law, named after a closed steel plant, gives double voting rights to investors who register shares in their name and hold them for at least two years.
Qatar said in its filing to French markets watchdog AMF that it could increase its stake further, but it had no plans to gain control of the company.
It also said it was considering seeking representation on Lagardere's supervisory board and was eyeing strategic partnerships, reiterating options already laid out in previous filings.
Lagardere, which will hold its annual shareholders' meeting on Thursday, has a limited partnership structure that gives the founding family near-absolute control and responsibility, even with a minority stake.
The group reported in March a 13.5 percent increase in full-year core operating profit to 395 million euros ($431 million) on group revenue of 7.39 billion euros, up 2.5 percent on a like-for-like basis.
Lagardere shares are up 7.75 percent so far this year, valuing the company at 3.7 billion euros. ($1 = 0.9168 euros) (Editing by Adrian Croft and Alexander Smith)