A newly-married couple pose for pictures in front of the Houses of Parliament, London, on Saturday. (Reuters)

London, Dec. 18 (Reuters): Fresh snow brought much of Britain to a standstill today, on what is traditionally the busiest weekend for shopping and travel in the run-up to Christmas.

Most of western Britain, Northern Ireland and northern Scotland suffered blizzards, while southern England was also blanketed in snow, disrupting trains and road traffic in what transport secretary Philip Hammond described as “extraordinary” conditions.

The Met Office issued a severe weather warning for London and southeast England, with up to 20cm of snow predicted.

Runways at both of Britain’s busiest airports, London Heathrow and London Gatwick, were closed to allow the snow to be cleared.

British Airways cancelled all flights from Heathrow and all European and domestic flights from Gatwick between 1000GMT and 1700GMT today.

About 200 of Gatwick’s 500 scheduled flights had been cancelled by mid-day, the second time this month that heavy snow had forced its closure.

Germany’s biggest airline Lufthansa today announced the cancellation of domestic and European flights to and from Frankfurt airport due to “an expected worsening of weather conditions”. It said long-range flights were not affected.

The Arctic conditions in Britain also hit rail and road travel, with the media reporting that hundreds of motorists were stranded in their cars in freezing conditions overnight in the northwest, with many accidents reported.

“We will be doing what we can to keep the transport network moving, but as I think is clear ... these are really quite extraordinary weather conditions, and we are expecting more heavy snow during the course of the day, particularly in southern England,” Hammond told BBC radio.

It is the third winter in a row that Britain has been left largely snowbound, and hit by record low temperatures.

Hammond said he had asked the country’s chief scientific adviser to see if it represented a “step change” in weather patterns due to climate change and whether the government needs to spend more money on winter preparations.

Some of the worst affected areas included Merseyside with 12-18cm of snow, and southwest England and Wales with 5-10cm, the Met Office said on its website.

The snow will blow into parts of southeast England and the south Midlands during today, with temperatures dropping to minus 14 degrees Celsius later in western Scotland.

Researchers warned on Thursday the severe weather conditions could push retailers into the red over the peak Christmas trading period, although a survey on Wednesday showed British retail sales rising at their fastest pace since 2002.

Some shoppers, hoping to avoid the treacherous conditions by purchasing presents online, faced disappointment after it was reported items were stockpiled in warehouses, with companies unable to deliver by road or rail.

Many Premier League football fixtures were called off, including tomorrow’s top of the table clash between Chelsea and Manchester United. Hammond said there was enough salt for the roads to deal with “a normal severe winter” but in extreme conditions it was less effective.

Airports in Germany, France, the Netherlands and Denmark also reported cancellations or delays. Hundreds of motorists were left stranded on the major M6 route in northwestern England.