Updated 09.07

Air passengers are being advised of disruptions and delays as a result of heavy fog.

Six flights to London have been cancelled and there are knock-on delays to other flights.

Aer Lingus says two of its services between Dublin and London have been cancelled: flight EI-154 (Dublin to London) and flight EI-155 (London Heathrow to Dublin).

Aer Lingus says those affected by these cancellations will be re-accommodated on alternative services.

They also have the option to rebook to another flight at no additional fee, or cancel booking and request a refund.

"Aer Lingus would like to advise guests booked to travel between Dublin, Cork, Shannon, Belfast and London Heathrow that they may experience further delays and cancellations to flights due to fog in the London area", the carrier says.

The UK Met Office has issued a yellow weather warning for most of England and parts of Wales.

Around 45 flights have been cancelled at London Heathrow and more than 20 have been cancelled at London City Airport.

A spokeswoman for the airport said: "We've got extra passenger ambassadors in the terminals to provide assistance for those travelling today.
"Once again we would like to apologise for the disruption".

Fog also caused widespread travel disruption on Sunday, with more than 50 flights at Heathrow cancelled.

Other airports affected included Gatwick, Birmingham, Leeds Bradford and Liverpool.

The fog is expected to slowly clear throughout the day.

A spokesperson for the DAA says conditions have improved this morning - but a number of flights into the London city area are cancelled and passengers are advised to check with their airline.

Siobhán O'Donnell, spokesperson for the DAA, spoke to Newstalk Breakfast  earlier.