The French government has cancelled plans to part-privatise nuclear power group Areva, claiming strategic and safety concerns for its U-turn.
Mr Villepin says other privatisations will continue
The announcement by Prime Minister Dominique de Villepin comes as privatisation plans continue for other state firms.
He said ongoing state control of Areva would ensure the necessary assurances.
Shares in Areva were due to be issued next year, with the sale set to raise up to 3.6bn euros ($4.4bn; £2.4bn).
Areva is the world's largest maker of nuclear power stations, operating all France's plants and other facilities around the globe.
Plans to part-privatise the business were first announced back in February.
"In a sector as strategic as the supply of fissile matter, enrichment and the treatment of nuclear waste, state control must supply the guarantees which are necessary to our citizens and our foreign clients," said Mr Villepin.
"You will understand that under these conditions, the opening of Areva's capital is not part of my government's agenda."
The French government is continuing with other part-privatisation plans, despite strong opposition from unions and workers.
On Friday a 15% stake is being sold in Electricite de France, and 22% of stock in Gaz de France was floated back in the summer.
Mr Villepin has also repeated plans to sell a majority stake in France's toll-road motorway operators.
"There still is a willingness by the government to go ahead with privatisations, but the issue has proved to be politically difficult, with trade union opposition," said Christian Parisot, an economist at Paris financial brokerage Aurel Leven.