Photo taken on Dec. 30, 2016 shows the Tower Bridge in fog in London, Britain. (Xinhua/Han Yan)

LONDON, Jan. 23 (Xinhua) -- London's major airports were badly affected Monday as a blanket of freezing fog hit large areas of Britain.

By midday more than 100 flights at London Heathrow, Britain's busiest airport, had been cancelled, while 65 were cancelled at London City Airport and a number were also cancelled at London Gatwick.

Luton and Stansted airports were able to continue to operate, with just a few delays.

Heathrow explained on its social media site why it has been badly affected by fog.

Its message said: "Bad weather of any type can create flight delays for arriving and departing aircraft at any airport around the world. Due to Heathrow operating at 98 percent capacity, the effects of fog on flights can be more noticeable than most airports.

"The vast majority of airports have spare runway capacity so aircraft can be spaced out more during fog without causing delays and cancellations."

"Heathrow is unusual in that it operates at 98 percent capacity, with a plane landing or taking off every 45 seconds. Without taking preventative action, spacing flights out more during fog inevitably causes delays and cancellations because there is simply no room to accommodate the delayed flights."

The day started with a fog warning issued by meteorologists at the Met Office, saying that a large area of southern England would be affected by low temperatures and freezing fog, with adverse weather continuing into Monday afternoon.

Passengers at all airports in the greater London area were being advised to check with airlines whether their flights had been cancelled or delayed because of the weather.

Parts of northern England were also affected by fog, with the possibility of flights from some provincial airports facing delays.

Fog also caused major problems for commuters on motorways and major roads as they headed to work.

Visibility on some roads made driving conditions hazardous, but there were no reports of any major road crashes caused by the poor visibility.

With temperatures in some parts of southern England down to minus 8 degrees Celsius during the night, weather forecasters said temperatures would struggle to climb above zero in many areas.