Image copyright EPA Image caption A blanket of freezing fog swept across London on Friday

Dozens of flights have been cancelled or delayed in and out of UK airports after fog hit parts of the country.

Heathrow, Gatwick, London City, Southampton and Cardiff airports all warned passengers to check with their airlines before travelling.

The Met Office expects the fog to clear by New Year's Day, when rain is expected to sweep south across England.

Meanwhile, Public Health England (PHE) warned that temperatures could plummet as low as -5C on New Year's Day.

Keep up to date with traffic and weather news on the BBC:

There has also been widespread disruption on the railways as a fresh strike by Southern Rail affects travellers.

Parent firm Govia Thameslink (GTR) has urged people to check travel information because some New Year's Eve services will finish early.

Met Office meteorologist Mark Wilson said Friday's freezing fog had lingered overnight and while much of it had lifted by Saturday afternoon, some patches could persist into the evening, "but not as widespread or as dense".

The Met has issued north-west Scotland with a "yellow" weather warning, with heavy rain and gale-force winds expected to bring difficult driving conditions ahead of Hogmanay celebrations.

'Very heavy fog'

A spokeswoman for Gatwick Airport, which cancelled 140 flights flights on Friday, said: "Unfortunately we are still experiencing very heavy fog across the south east."

She said a number of crew members had been displaced by Friday's cancellations, which may be contributing to the further delays.

More than a dozen easyJet flights were delayed for over an hour on Saturday morning, she added.

Image copyright Getty Images Image caption Some 45 flights were cancelled at Heathrow on Saturday

Though Gatwick is not experiencing any further cancellations, the airport "strongly advises" people to contact their airline before travelling.

A spokesman for Heathrow Airport said 45 flights had been cancelled on Saturday after being displaced by Friday's fog.

He said there were no further cancellations due to Saturday's weather conditions but warned there might be some delays.

London City Airport also warned Friday's fog had led to a number of cancellations and diversions on Saturday, telling travellers on Twitter to check the status of their flights.

Southampton Airport in Hampshire and Cardiff Airport also reported disruption due to fog on Saturday morning and advised passengers to check their flights.

'Explosive' frustration

Image copyright PA

British Airways passenger Alexander McNabb and his wife Sarah's flight from Belfast to Heathrow has been delayed by more than 24 hours.

Mr McNabb, who is due to spend New Year's Eve with family before flying home to Dubai, told the BBC his frustration was "explosive".

He said: "Our flight was cancelled and we were given an awful handwritten note with the wrong contact number on it, and a £5 compensation voucher."

After exhausting every customer helpline with no luck, Mr McNabb finally got a response from BA through Twitter.

"They told us to come back to the airport at 6am, so we got up early. We checked in. Then it turns out there's a plane but no crew... And we've been delayed until 5.30pm.

"They gave us another £5 voucher for breakfast... We're checked in and trapped in."

A spokesman for BA apologised for Mr McNabb's delay, blaming Friday's fog for putting crews and aircraft out of position.

Meanwhile, Highways England said the foggy conditions of recent days underlined the importance of driving to the conditions.

Seventeen people were injured on Friday after a coach veered off a motorway slip road and overturned in heavy fog in Oxfordshire.

A spokesman for Highways England said: "Fog can come very quickly so it's important to leave plenty of space.

"The thing that's really important to remember is when it's wet it does take twice as long to stop."