FREEZING fog and plummeting temperatures have brought fresh travel disruption to the UK.

Motorists were warned that roads could become "lethal" due to the hazardous combination of poor visibility and the onset of ice, the AA said.

Heathrow Airport was also hit by delays as fog blanketed England, crippling London City Airport for a second day with more than a dozen flights cancelled or held up.

Luton airport also faced disruption after a technical issue with its air traffic control slowed departures.

Sub-zero temperatures swept across the UK on Thursday morning, with the mercury dipping to freezing levels in areas such as Suffolk, Gloucestershire, Cumbria, Devon and northern Scotland, the Met Office said.

It follows a fatal pile-up on the A40 in treacherous conditions on Wednesday morning, which left one woman dead and many injured.

The Met Office issued a "yellow" fog warning for much of England, which said visibility could drop below 100 metres in some areas.

It said: "Combined with temperatures below freezing, there is also the risk of ice forming on some untreated surfaces particularly later in the night and early on Thursday morning.

"The fog patches are expected to slowly thin during Thursday, although some patches may persist throughout the day - most likely in a zone from the West Country to Eastern England."

A spokesman said on Thursday morning that fog had been recorded across England and was particularly thick in areas such as Lincolnshire.

The AA urged "extreme caution" for those heading out on the roads, adding that extra time should be allowed, tyres properly inflated and screens adequately de-iced.

Spokesman Ian Crowder said: "We have got the worst possible conditions really, of fog and icy roads, and that can be lethal.

"I think the message is extreme caution and to prepare for the worst and make sure all windows are clear."

He added that failure to do so could "lead to disaster".

At London City Airport, passengers were warned to expect knock-on delays throughout Thursday due to the raft of disruptions and advised to check details with their airlines,

Meanwhile, a spokeswoman for Heathrow said they hoped delays would end by mid-morning, adding: "When there is fog we allow for a little extra space between aircraft, this is standard operating practice."

On Wednesday, Public Health England (PHE) issued advice for the over 65s, those with long-term illness or who are not mobile.

Dr Thomas Waite, consultant in extreme events and health protection at PHE, said: "The effects of cold can be severe, in particular for those who are over 65, have a long-term illness, or are not mobile. Our advice to these groups is when indoors, have plenty of warm food and drinks and try to maintain indoor temperatures to at least 18C.

"If mobility isn't an issue, keep active as best you can. If you need to go out wear lots of thin layers, and shoes with a good, slip-resistant grip to prevent any accidental falls. It is particularly cold at night this week, so drawing the curtains at dusk will keep the heat in."