Prime Minister Boris Johnson initially refrained from approving the stringent controls that other European leaders imposed but then closed down the country when projections showed a quarter of a million people could die in the United Kingdom.

So far, more than 12,000 people with COVID-19 have died in British hospitals, though new official data indicates the true death toll could be much larger.

“I think that some of the decisions made in the last few weeks were too slow and didn’t learn quickly enough from other countries, let’s not repeat that,” Starmer told BBC Radio.

Starmer, a 57-year-old former prosecutor who won the leadership of the Labour Party earlier this month, is calling on the British government to publish its exit strategy from lockdown restrictions.

Governments around the world are grappling with how to reverse measures put in place to contain the outbreak and which are battering the global economy. Several European countries have announced plans or already begun to relax restrictions.

Starmer said mass testing was likely to play a big role in any exit strategy and the government needed to put the necessary planning, investment and infrastructure in place early.

Foreign minister Dominic Raab, who is deputising for Johnson while he recovers from COVID-19, said on Monday he did not expect to make any changes to the restrictions for now. They are due to be reviewed on Thursday.

Starmer said Labour supported extending the measures in Britain but that to “maintain morale and hope”, the public needed to have an idea of what is coming next.

“Overcoming this crisis requires taking the British public with you,” Starmer said. “The government needs to be open and transparent... The silent pressures on communities across the country cannot be underestimated.”

A British government source said all decisions would be guided by scientific advice and data.

“Talk of an exit strategy before we have reached the peak risks confusing the critical message that people need to stay at home in order to protect our NHS (National Health Service) and save lives,” the source said.

The government promised on Wednesday to test all residents and employees of nursing homes who have COVID-19 symptoms after official data showed the death toll from the pandemic was far higher when the elderly in care were included.