Transport operators are under severe pressure to get the Christmas getaway back on track after days of disruption caused by the snow.

Heathrow Airport's second runway reopened on Tuesday night, raising hopes for the thousands of stranded air passengers - many of whom have spent uncomfortable nights in the terminals.

It told passengers to check online a list of flights that airlines have said will operate, and not travel to the airport unless the departure was confirmed.

On the trains, Eurostar said it was operating a near-normal service. But the operator asked only people with tickets for travel today to turn up at the station.

Snow was falling across north Wales, the Midlands and parts of the North East this morning. Heavy snow warnings are in place for Wales, the North West, West and East Midlands, eastern England and the South West.

Prime Minister David Cameron expressed his "frustration" at the length of the disruption at Heathrow, while airlines accused BAA of failing to have enough de-icer to cope with the situation.

Wolfgang Prock-Schauer, chief executive of airline BMI, told The Times the Heathrow situation was "completely unacceptable". He said: "BAA was not prepared. It did not have enough de-icing fluid."

The EU Commission also slammed Europe's air travel disruption as unacceptable and urged airports to "get serious" about better planning for bad weather.

BAA chief executive Colin Matthews warned people not to expect normal services immediately and urged them to check before going to the airport. He also pledged to investigate how the situation was dealt with and why it took so long to clear snow from aircraft - but only after the "short-term" aim of getting passengers to where they needed to be had been achieved.

Andy Ratcliffe, forecaster at MeteoGroup, the Press Association's weather division, said Heathrow and Gatwick could expect temperatures of 1-2C, with no end to the freezing conditions.