The Spanish state weather agency, Aemet, has warned that sub-zero temperatures and thick fog will sweep across central, northern and eastern parts of Spain on Thursday.

According to the agency, the mercury will drop to as low as -6C on Thursday, while foggy conditions will reduce visibility to as low as 100 metres.

These conditions could put many flights at risk from delays and cancellations, after similar conditions in the UK this week resulted in similar consequences.

A yellow-level alert is in place for cold in Segovia, Sierra de Madrid, Soria, Guadalajara, Calatayud, Burgos, Lleida, inland Barcelona and more.

In all areas the temperature will be between -4 and -6C, with the warning in place for the whole of Thursday.

Meanwhile, a yellow-level alert is in place in multiple areas for intense fog, including Huesca, Zaragoza, La Rioja, Navarra, Meseta de Burgos, Meseta de Palencia, Valladolid, Leon, Zamora, Salamanca.

Visibility in these areas will be reduced to between 100 and 200 metres, Aemet has reported.

This puts flights at airports in Salamanca and La Rioja at risk, considering special measures are typically implemented when visibility reduces to 600 metres.

Tens of thousands of passengers in the UK had their Christmas travel plans disrupted last week as thick fog descended on airports.

Budget airline easyJet said a number of its flights at Gatwick Airport were "unable to operate as planned" due to the "poor weather".

Around 30 departure flights and 28 arrivals were cancelled out of 769 flights on Sunday (December 29) - the busiest day of the Christmas period for the airport.

Patches of thick fog saw visibility reduced to just 100 metres in some areas, the Met Office said.