France's richest man boss Bernard Arnault must size up the implications of seeking Belgian nationality, President Francois Hollande says, vowing no exceptions to a stinging wealth tax plan.
"He must weigh up what it means to seek another nationality because we are proud to be French," Mr Hollande said in a television interview, adding there would be no exceptions to a 75 per cent tax on incomes above one million euros ($A1.24 million).
"One has to appeal to patriotism during this period," Mr Hollande said.
He added that the proposed tax would "affect between 2000 and 3000 people" and ruled out exemptions for top professional footballers and performers.
"This will be an exceptional contribution ... all incomes higher than one million euros will attract 75 per cent tax," the French leader said.
"To be French is to receive and give back to the country, it's patriotism and everyone must play his role."
Mr Arnault, head of luxury goods group LVMH (Moet Hennessy Louis Vutton) said on Sunday he was not becoming a tax exile, despite seeking Belgian nationality.
"I am and will remain a tax resident in France and in this regard I will, like all French people, fulfil my fiscal obligations," the world's fourth-richest man told AFP.
"Our country must count on everyone to do their bit to face a deep economic crisis amid strict budgetary constraints," he said, adding that the bid for dual nationality was "linked to personal reasons" and began several months ago.
An informed source told AFP that Mr Arnault's move, news of which was broken by Belgian newspaper La Libre Belgique, was linked to a "sensitive" investment project that could be made easier if he acquired Belgian nationality.