UK ministers will hold an emergency meeting after meteorologists warned of record high temperatures in England that could put lives at risk.

Cabinet Office minister Kit Malthouse will chair the meeting to discuss the escalating heatwave, a Government spokesman said, the second such meeting he has led on the issue.

Meteorologists have given an 80 per cent chance of the mercury topping the UK's record temperature of 38.7C set in Cambridge in 2019, with the current heatwave set to peak on Tuesday.

Temperatures will climb during the weekend, and the Met Office has issued an amber warning for heat covering much of England and Wales from Sunday until Tuesday.

London Mayor Sadiq Khan held a special meeting with key officials to ensure a robust plan is in place to deal with the level four heat alert.

Khan has urged Londoners to undertake only essential travel on Monday and Tuesday and to prepare for disruption because speed restrictions will be in place on rail and Tube networks.

A high air pollution alert for London has also been issued for Monday.

Daytime temperatures on Saturday are predicted to be about 27C in London, 26C in Cardiff, 23C in Belfast and 21C in Edinburgh.

On Sunday, it could reach 30C in the capital, 27C in Cardiff, 24C in Belfast and 23C in Edinburgh.

Temperatures are forecast to increase by several more degrees on Tuesday - up to the mid-30s for much of England and Wales.

There is a 50 per cent chance of temperatures reaching 40C somewhere in the UK, likely along the A1 corridor which runs from London to Scotland through counties including Lincolnshire, Nottinghamshire, Yorkshire and the North East, with the Met Office issuing its first-ever red warning for extreme heat.

The UK Health Security Agency has increased its heat health warning from level three to level four - a "national emergency".

A Met Office red warning, for Monday and Tuesday, covers an area from London up to Manchester, and up to the Vale of York.