France has imposed a month-long lockdown on Paris and parts of the north after a faltering vaccine rollout and spread of highly contagious coronavirus variants forced President Emmanuel Macron to shift course, Reuters reports.

His prime minister, Jean Castex, said France was in the grip of a third wave, with the virulent variant first detected in Britain now accounting for some 75 per cent of cases. “The epidemic is getting worse. Our responsibility now is to not let it escape our control,” Castex told a news conference.

“Four weeks, the time required for the measures to generate a sufficient impact. [It is] the time we need to reach a threshold in the vaccination of the most vulnerable.”