British Prime Minister Boris Johnson on Sunday unveiled a "conditional plan" to reopen society, allowing people in England to spend more time outdoors from Wednesday.

The PM said people who could not work from home should return to the workplace – but avoid public transport.

He said a new COVID alert system with five levels will govern how quickly lockdown restrictions can be eased.

He hoped the next step "at the earliest by 1 June" will allow some primary pupils to return to school in England.

In an address to the nation, Johnson said this stage will also involving reopening shops, but he cautioned this will only happen if the science supported it.

The next step could see some of the hospitality industry and other public places reopen – "if the numbers support it" – and no earlier than July 1.

The PM added: "This is not the time simply to end the lockdown this week. Instead, we are taking the first careful steps to modify our measures."

Johnson's speech came hours after Scottish First Minister Nicola Sturgeon said she felt ending the previous "stay at home" message was the wrong choice for Scotland.

The PM earlier unveiled the new message of "stay alert, control the virus, save lives" in England – but Ms Sturgeon said it would not apply in Scotland at the moment.

Wales' health minister Vaughan Gething also said there had not been a "four-nations agreement" on the new message and that the advice to "stay at home" in Wales was unchanged.

Scotland, Wales and Northern Ireland have powers over their own lockdown restrictions, with England's measures set by the government at Westminster and leaders have expressed a wish to move forward as one – though they may do so at different speeds.