Storm Eunice is causing travel chaos, with hundreds of flights cancelled, rail lines blocked and road bridges closed.

A rare “do not travel” alert was issued across Britain’s railways, as seven operators suspended all services.

More than 430 flights due to take off or land at UK airports were cancelled on Friday.

Meanwhile, both the M4 Prince of Wales Bridge and the M48 Severn Bridge, which link England and Wales across the River Severn, were closed due to high winds.

It is believed to be the first time both crossings have been closed simultaneously.

The train operators which stopped running all services on Friday afternoon were: c2c, Chiltern Railways, Great Western Railway, Greater Anglia, South Western Railway, Southeastern and Transport for Wales.

Network Rail closed all routes in Kent, while every line in south-east London was blocked by trees.

Many journeys were already delayed as the organisation implemented widespread emergency 50mph speed limits before the bad weather arrived to make it easier for train drivers to brake.

Passengers were urged not to travel.

Jacqueline Starr, chief executive at industry body, the Rail Delivery Group, said: “Storm Eunice is causing widespread damage and we’ve had to respond by closing lines to keep our customers and staff safe.

“We’re telling people not to travel today and instead to claim a fee-free refund or use their ticket over the weekend.”

The Port of Dover announced it was closed “in the interests of customer and staff safety”, meaning no ferries could operate between Dover and Calais.

Several sailings across the Irish Sea were also cancelled.

Aviation analytics firm Cirium said at least 436 UK flights were cancelled on Friday.

Heathrow suffered the worst disruption, with a fifth of all flights cancelled.

This was followed by London City (16%) and Manchester (10%).

Planes are struggling to land at airports due to high winds, with many being diverted or requiring several attempts before touching down.

Several planes reached the skies above their arrival airport, but were forced to return to their starting points.

They include an easyJet flight from Bordeaux, France, to Gatwick, a British Airways flight from Edinburgh to Heathrow and a Lufthansa flight from Munich to Heathrow.

British Airways flight BA296 from the US city of Chicago was due to land at Heathrow but was diverted to Geneva, Switzerland.

A flight by the same airline from Venice, Italy, to Heathrow landed at Newcastle instead.

British Airways said: “Due to the extreme weather conditions across the UK and resulting restrictions on the number of aircraft that can take off and land each hour, we, like other airlines, are experiencing significant disruption.

“We’re operating as many flights as we can and putting on larger aircraft where possible.”

National Highway, which operates the Severn bridges, said its staff were “being abused” for taking action to “keep road users safe”.

Traffic Wales, the Welsh Government’s traffic information service for motorways and trunk roads, warned that “many HGVs are ignoring the safety advice on Britannia Bridge”.

The bridge, which connects the island of Anglesey with mainland Wales, is closed to all traffic except cars and car-derived vans.

There were one-hour delays on the M25 due to the closure of the Queen Elizabeth II bridge, which is part of the Dartford Crossing.

The RAC said the number of call-outs to broken-down vehicles was lower than normal, indicating that many people were “taking the weather warnings seriously and not setting out”.

It added: “The fact many roads are so clear is a sign that today is not a safe day to be driving.”

Transport for London urged people to avoid non-essential journeys in the capital.