Prime Minister Boris Johnson insisted Wednesday that a looming new coronavirus lockdown for England would end "automatically" in four weeks, as he tried to placate party critics over the spiralling economic fallout.

Following a first lockdown in March, the second round of restrictions will come into effect at 0001 GMT Thursday, but Johnson told parliament the measures would be lifted in time to give England the chance of a more normal Christmas.

Last weekend, Johnson abandoned a new system of regional curbs and announced an England-wide lockdown after dire warnings that hospitals could soon be overwhelmed with Covid-19 cases.

Senior minister Michael Gove then indicated the lockdown could last beyond a December 2 cut-off if it failed to bring infection rates down.

And the leader of the main opposition Labour party, Keir Starmer, told Johnson in parliament that it would be "madness" to end the measures on schedule if cases are still rising.

But the prime minister pointed to plans to launch Friday a city-wide testing pilot scheme in Liverpool as a precursor to a nationwide programme, and said the lockdown would "end automatically on December 2".

"We will then, I hope very much, be able to get this country going again, to get businesses, to get shops open again in the run-up to Christmas," Johnson said.

Britain is among the world's hardest-hit countries with nearly 48,000 deaths linked to the coronavirus from just over one million positive cases.

A total of 492 deaths, within 28 days of a positive test, were recorded on Wednesday -- the highest since mid-May.

England will join the other nations of the UK -- Scotland, Wales and Northern Ireland -- in imposing another lockdown, in line with European nations including France and Germany.

"When I look at what is happening now among some of our continental friends, and I see doctors who have tested positive being ordered to work on Covid wards and patients airlifted to hospital in some other countries simply to make space, I can reach only one conclusion," Johnson said.

"I'm not prepared to take the risk with the lives of the British people."

The English lockdown measures include a return to working from home where possible and the closure of all non-essential shops and services, including pubs, bars and restaurants.

Britain's Prime Minister Boris Johnson leaving Downing Street for parliament on Wednesday
Britain's Prime Minister Boris Johnson leaving Downing Street for parliament on Wednesday AFP / DANIEL LEAL-OLIVAS

Hours before they take effect, the measures were overwhelmingly passed in the House of Commons, but 38 MPs voted against.

Some members of Johnson's own Conservative party are deeply unhappy at the impact on the economy, on civil liberties and on mental health.

"I decided that what we were being fed was propaganda and not the full facts," Tory backbencher Peter Bone told the PA news agency, unswayed by a briefing by government scientists and direct talks with Johnson in recent days.

But the National Health Service, which runs state hospitals, said the autumn resurgence of Covid-19 was forcing it to adopt an emergency footing when the new lockdown comes into force.

"Unfortunately we are once again facing a serious situation," NHS England chief executive Simon Stevens told a news conference.

"This is not a situation anybody would like to find themselves in."

Finance minister Rishi Sunak will detail new financial support measures on Thursday, the government said.

Also Thursday, the Bank of England is expected at its latest policy meeting to boost its cash stimulus to fight the pandemic's economic fallout.

The UK central bank is widely predicted to pump out an extra ?100 billion ($130 billion, 111 billion euros) under its long-running "quantitative easing" programme, bringing the total to ?845 billion.

The BoE is also likely to revise down its forecasts for UK economic growth, amid deadlock over Britain's post-Brexit trade agreement with the European Union.

Brexit and the pandemic pose a double-whammy for hard-pressed companies, many of whom have been laying off staff despite direct government support for wages.

Department store chain John Lewis said it was cutting 1,500 jobs, while retailer Marks & Spencer posted its first-ever loss.