Thousands of families were told yesterday they could have a miserable Christmas because online gifts may not be delivered and homes could go without heating.

A backlog of around four million parcels has developed as private carriers struggle to overcome delays caused by the snow and ice.

And with the predicted second big freeze about to grip Britain it will only get worse, experts said.

This could also have an impact on Malta, as popular sites such as Play.com, Amazon and others still, have proven to be highly sought after with those wanting to avoid the shops and seeking to get their Christmas shopping done from the comfort of their own home.

The news came as MPs were told rocketing oil prices and restricted deliveries could also mean thousands of homes going without heating this winter.

The government admitted the situation could become "very serious" if it snows again. Many homes may have to wait for as long as four weeks for oil to be delivered. In the last month alone prices jumped from under 40p a litre to more than 70p in some cases, amid allegations oil companies are fixing their prices.

The Office of Fair Trading will look for any cases of price-fixing, Energy Minister Charles Hendry told the Commons.

Parcel and carrier management firm Global Freight Solutions said it could be the first year in which depots and offices do not clear all their gifts.

"This year in Scotland and the North East it is likely Father Christmas won't be coming," said Simon Veale, director of the company.

Dealing with the backlog was like "bailing water out of a sinking ship".

Mr Veale went on: "There are likely to be more than four million new parcels in the system every day this week on top of several million more which still had to be cleared from the recent extreme weather.

"No one in the industry likes the prospect of not making collections or deliveries and everyone's working around the clock to do what they can to ensure that items arrive on time but the reality is that some will not.

"We are being told by certain of our carrier partners that things are so severe in Scotland that they're running out of trailers in the rest of the country, impacting on deliveries in England and Wales.

"If there are additional falls of snow, as the weather forecasts are suggesting, the unhappy situation will be compounded further still."

Carriers began restricting the number of non-urgent packages they will deliver to try to ensure essential items reach their destinations on time, he added.

The Royal Mail delivered 7,000 rounds on Sunday to around one million addresses.

Managing director Mark Higson said: "This is already the worst December weather the UK has seen for almost 30 years."

The Association of Train Operating Companies said it will run "ghost trains" to help keep routes open and have hundreds of ground staff on duty to try to keep key junctions and points clear of snow, as well as clearing and gritting platforms and station approaches to improve passenger safety.

Robin Gisby, Network Rail's director of operations and customer services, said: "We have pulled in even more manpower and machinery to help tackle the bad weather ahead.

"Thousands of our people will be out overnight working to keep routes open, keep trains running, to offer the best possible service we can."

Meanwhile, the Local Government Association and Highways Agency urged motorists to be careful on the nation's treacherous roads.

Council gritting crews will be out in force, according to councillor Peter Box, who chairs the LGA's economy and transport board.

He said: "Salt is a precious commodity at this time of year and councils have been given guidance from the government on how to use it carefully and to the maximum effect.

"While we are aware of the need to conserve salt for what is expected to be a long, cold winter, councils are committed to ensuring that roads are properly treated and will not compromise on safety."

Forecasters predicted snow will begin to fall today, with heavier showers from Friday evening going into the weekend.

Andy Ratcliffe, a forecaster with Meteogroup, the Press Association's weather centre, said rain and snow showers will fall across Scotland and the North East.

He said: "Overnight it's very cold with widespread frost and continuing snow showers in Scotland, Northern Ireland, Wales and south-west England. It's very cold everywhere."

The temperature may reach as low as -10°C in Scotland and -5°C in south-east England.

Today, temperatures across the UK may not get above freezing.