Around 600,000 people were forced to cancel their flights in December from Heathrow airport. 

Many of the cancellations are said to be caused by the surge of the Omicron strain across the county and the introduction of tougher travel restrictions. 

From late November, travelers arriving in the UK had to take pre-departure lateral flow tests and self-isolate until they received a negative result.

The new restrictions led to many people scrapping their travel plans over the Christmas period. 

This Is Local London: Flights were cancelled due to travel restrictions. (PA)Flights were cancelled due to travel restrictions. (PA)

However, the rules were relaxed for fully-vaccinated arrivals last week when travel firms said they were ineffective as Omicron had already spread across the UK. 

Across the whole of last year, a total of 19.4 million people traveled through the major airport. 

This is less than a quarter of pre-pandemic levels in 2019 and 12.3% down in 2020. 

Heathrow chief executive John Holland-Kaye said: “There are currently travel restrictions, such as testing, on all Heathrow routes.

“The aviation industry will only fully recover when these are all lifted and there is no risk that they will be reimposed at short notice, a situation which is likely to be years away.”