A deal between AstraZeneca and France over potential COVID-19 vaccines involves doses being split between countries on a pro-rata basis based on population, a source at the French President's office said on Monday.

The British drugmaker signed a contract with European governments at the weekend to supply the region with up to 400 million doses of its potential vaccine.

It was the first contract signed by Europe's Inclusive Vaccines Alliance (IVA), a group formed by France, Germany, Italy and the Netherlands to secure vaccine doses for all member states as soon as possible.

"The principle of the deal is that the vaccines will be distributed pro rata, based on population," the source at the French president's office said. "What we've asked for and what has been agreed is for production to take place in Europe."

France hopes to strike similar deals with other pharmaceuticals companies soon, the source added.

The vaccines - still in clinical trials - would be for all EU member states.

Governments have been scrambling to secure advance purchases of promising coronavirus immunisation treatments amid concerns within the EU that the bloc has not moved fast enough compared with other regions or countries.

In France, Sanofi's call in May for a more collaborative European effort in the hunt for a vaccine sparked a backlash, especially after the French drugmaker's CEO said doses produced in the United States, which had rapidly rolled out funding for research, would go to U.S. patients first.

Sanofi Chief Executive Paul Hudson later tempered his comments, emphasising that any coronavirus vaccine would reach all parts of the world.

Macron is due to visit a Sanofi Pasteur vaccine plant in France on Tuesday and will announce commitments on treatments and manufacturing capacities alongside the company, the source at the President's office said.