Travellers struggling to get home for Christmas faced another day of chaos on Friday, with some 350 flights cancelled at London's Heathrow Airport for a second day due to a thick blanket of fog.

But some relief was in sight, with British Airways, which has suffered most cancellations, saying it aimed to fly 95 percent of customers in and out of Heathrow as planned on Saturday.

The airline said it planned extra flights with bigger planes to try to ease disruption as the fog begins to clear.

"We are hopeful that the weather will improve slightly over the weekend and therefore we can get back to operating a full planned Christmas Eve schedule," said Geoff Want, the airline's director of ground operations.

"We are drafting in extra staff from across the airline over the weekend to ensure that customers get to their final destinations before Christmas Day."

Britain's Met Office predicted widespread fog for Saturday, possibly lingering in some areas on Sunday, Christmas Eve.

On Thursday, 350 flights were cancelled and a similar number were stopped on Friday, said a spokesman for airport operator BAA, which runs Heathrow and six other British airports.

BA said it was offering customers "the three Rs -- rebooking, rerouting and refunds". In below freezing conditions, passengers were offered hot drinks, woolly hats and blankets by staff.

"Christmas has been cancelled," complained disgruntled passenger David Page.

Father Christmas tried to offer some cheer to demoralized passengers with three red and white suited Santas despatched to raise morale at overcrowded terminals.

"We understand that Christmas is an extremely important time of year for our customers and their families and we are working around the clock to give every assistance possible," Want said.

Despite air traffic control rules which slowed landings and take-offs by 50 percent, a BA spokesman said the airline managed to get 80 percent of passengers to their destinations on Thursday, some going by minibuses or coaches.

BA has booked 5,000 hotel rooms over the past two nights to accommodate others.

Thousands packed on to trains to try to get home, said Virgin Trains, which runs long distance services across Britain. But there were no seats available on any of Friday's Eurostar trains from London to Paris or Brussels. Tickets are sold out until Saturday afternoon.

There were a small number of flight cancellations at London's second biggest airport Gatwick on Friday and some delays of up to an hour, BAA said, but no cancellations at the capital's third airport, Stansted.

The fog chaos and loss of revenue from hundreds of cancelled flights is expected to cost BA millions of pounds.

BA published quarterly earnings last month which showed it cost the airline GBP100 million pounds (USD$196.5 million) after security was tightened in the wake of what police in August said was a plot to blow up airliners.