Motorists were advised to take care if they had to travel, and the Highways Agency said "continuous salt treatment" was being carried out at high-risk areas.

司机被提醒若必须驾车外出一定要小心行驶，而高速公路局说会在高风险地区进行“持续的撒盐行动”。

youdao

However, a Highways Agency spokesman said that the southbound carriageway of the motorway would remain shut between junctions one and four "until it is safe to be reopened".

然而，一名高速公路局地发言人说，南向的高速公路仍会保持关闭状态，直到1、4号路口“足够安全”。

youdao

The Highways Agency said normal traffic conditions would not return to the M4 until 2300 GMT.

BBC: Snow latest across the UK

The Highways Agency said control centres had been opened in every region in England.

BBC: NEWS | UK | England | 'Jam busters' take to the roads

The Highways Agency said a number of roads were closed due to the snow.

BBC: Schools and airports closed after heavy snow in England