Image copyright Reuters Image caption Sanofi's HQ is in Paris and the firm has received French state tax breaks
France has said it would be "unacceptable" for French drug giant Sanofi to prioritise the US market if it develops a Covid-19 vaccine.
The government was reacting to remarks by Sanofi CEO Paul Hudson, who said "the US government has the right to the largest pre-order because it's invested in taking the risk".
Prime Minister Edouard Philippe said access for all was "non-negotiable".
Many labs worldwide are involved in research to find a Covid-19 vaccine.
Vaccines usually take years to develop.
"For us, it would be unacceptable for there to be privileged access to such and such a country for financial reasons," Deputy Finance Minister Agnès Pannier-Runacher told France's Sud Radio.
The prime minister later tweeted that a vaccine should be for the benefit of everyone worldwide. President Emmanuel Macron said that recent efforts proved that a vaccine should not be subject to market forces, the Elysée Palace said. He is due to meet top Sanofi officials next week.
Earlier this month the EU chaired a global online summit to boost coronavirus research, and secured pledges of $8bn (£6.5bn) from some 40 countries and donors. The funding is aimed at developing a coronavirus vaccine and treatments for Covid-19.
The UK co-hosted the summit but the US and Russia did not take part.
The EU insisted on Thursday that all countries should get equal access to a vaccine.
"The vaccine against Covid-19 should be a global public good and its access needs to be equitable and universal," said European Commission spokesman Stefan de Keersmaecker, quoted by AFP news agency.
Sanofi's Covid-19 vaccine research is partly funded by the US Biomedical Advanced Research and Development Authority (Barda).
But in recent years Sanofi has received tens of millions of euros in tax credits from the French government to help its research.
Mr Hudson's remarks in a Bloomberg interview provoked uproar among politicians on the right and left in France. The Socialists estimated that Sanofi had received some €150m (£133m; $162m) in research tax credit and millions more in other tax credit.
On Thursday Sanofi's chief in France, Olivier Bogillot, said "the goal is to have this vaccine available to the US as well as France and Europe at the same time".
Speaking on French news channel BFMTV, he said that would only be possible "if Europeans work as quickly as the Americans", and added that the US government had pledged to spend "several hundreds of millions of euros".
The row was reminiscent of reports in March of a US attempt to buy German biotech firm CureVac, which has also been researching a possible vaccine. CureVac insisted there had been no US attempt to buy the firm or its manufacturing capacity.
The French prime minister said he had spoken to Serge Weinberg, chairman of Sanofi's board of directors. "He's given me all the necessary assurance regarding the distribution of an eventual Sanofi vaccine."
Last month Sanofi also teamed up with Britain's GlaxoSmithKline (GSK) to work on a vaccine, though trials have not yet started.
Sanofi's head of vaccine research, John Shiver, says "we are using an existing technology that was designed for influenza, and we're applying it to the new virus that causes Covid-19 disease".
Sanofi says GSK "will contribute its adjuvant technology, an ingredient added to enhance the immune response, reduce the amount of vaccine protein required per dose and improve the chances of delivering an effective vaccine that can be manufactured at scale".
The candidate vaccine is expected to enter clinical trials in the second half of 2020 and to be available by the second half of 2021.