French President Emmanuel Macron will address the nation on Wednesday evening, his office said, as a fast-spreading third wave of COVID-19 infections threatens to over-run hospitals.

Macron has sought to avoid a third large-scale lockdown since the start of the year, gambling that if could steer France out of the pandemic without locking the country down again he would give the economy a chance to recover from a deep slump.

However, in recent weeks his options have narrowed as the highly contagious and virulent coronavirus variant first detected in Britain swept across France and much of Europe.

The number of patients in intensive care breached 5,000 on Tuesday, the highest number this year and exceeding the peak hit during a six-week long lockdown in the autumn. Thousands of school classes have been closed down.

Macron was holding a weekly COVID defence council on Wednesday morning. A government source told Reuters three scenarios were being examined: a massive operation to transfer intensive care patients from overloaded hospitals to lesser-hit regions; school closures; strict lockdown in the hardest-hit parts of France.

France faces having to tighten measures just as neighbouring Britain slowly emerges from a lockdown imposed in early January.

Macron had hoped France's COVID-19 vaccine campaign would reduce the numbers falling gravely ill. But the vaccine rollout is only now finding its stride three months after it began, with just 12% of the population inoculated.

The president will deliver his televised address at 8 p.m. (1800 GMT).

"What we needed earlier was a strict lockdown and huge vaccination drive, but it's still not too late," Gilbert Deray, a senior clinician at the Pitie-Salpeterie hospital in Paris told Europe 1 radio.

France used medical evacuations to ease the load on overwhelmed hospitals during the first two waves of the epidemic but there has been more resistance from families in recent weeks. The government source said the evacuations under discussion would not require family consent.

Paris mayor Anne Hidalgo told BFM TV that schools should be closed.

Ten days ago, the government closed non-essential stores and limited people's movements in Paris and other regions ravaged by the virus. Mobility data analysed by Reuters showed those measures were having markedly less impact than prior lockdowns.