The machines, branded as Hotpoint or Indesit, were sold for more than five years, but their door locking system can overheat creating the risk of fire.

Owners face the prospect of doing without hot washes for months until products are fixed or replaced.

Whirlpool was already reeling after problems with fire-prone dryers.

It was heavily criticised for its initial response when more than five million tumble dryers, sold over 11 years, were found to be a fire danger. It only launched a full recall for that issue after four years, following an intervention by the regulator. This time it has gone straight to a recall.

What is the new problem?

About 20% of the Hotpoint and Indesit washing machines sold since 2014 are affected by the fault. Up to 519,000 washing machines sold in the UK are involved.

Seventy-nine fires are thought to have been caused by the fault which develops over time, according to Whirlpool, which owns the brands.

"When the heating element in the washing machine is activated, in very rare cases a component in the door lock system can overheat, which, depending on product features, can pose a risk of fire," Whirlpool said.

The extra current that runs through the machine when the heating element is on can cause the door locking system to overheat.

The company said the issue had been identified by its safety team, but had led to fires, although none had been significant enough to cause more than minor damage or cause any serious injuries.

Engineer Colin O'Neill, who runs CJM Washer Services, said he was not surprised at the recall because he had seen failings connected to the door lock "for quite some time now".

He said: "When we go out, we remove the door lock and quite often find it has either failed or quite often we find that there's actually signs of burning to the door lock wiring harness.

"Sometimes I've even seen burn marks up the inside of the cabinet of the washing machine, so it looks like there has been a little mini fire there, but the customer hasn't known anything about it."

Steve Smithson from Romford, Essex was forced to call in an engineer when he had noticed a smell of burning and smoke coming out of his Hotpoint washing machine.

He said: "I immediately jumped up and turned the plug off, took the washing out - it really smelled - and checked the code. It said faulty door lock code."

What should I do if I think I own one?

Whirlpool has set up a model checker online, although this itself appears to have crashed. Owners of Hotpoint and Indesit washing machines bought since October 2014 will need to enter the model and serial number of their appliance - found inside the door or on the back - to see if it is one of those affected.

"We apologise to our customers for the technical issues they may be experiencing with our website. The issue is due to a third party system provider. We understand that it is not related to traffic to the website," Whirlpool said.

"The system provider is working to fix the issue as quickly as possible and the website should be back up shortly."

There is also a free helpline, open every day, available on 0800 316 1442, but this too was initially telling callers it was "unobtainable".

If owners eventually access these channels and find their machine is affected, to eliminate any risk, the appliance should be unplugged and not used until it is repaired in their home by a trained engineer, Whirlpool said. As an alternative, those affected will also be offered a replacement with a safe model.

Owners can check and register for a repair or replacement now. Vulnerable customers will be prioritised, but for others it may be organised on a first come, first served basis.

When will affected machines be fixed or replaced?

The process will not begin until early January, at the earliest, and the company would not be drawn on when everyone's case will be dealt with.

As a result, it could be months, not just during Christmas, that owners will have to cope without their washing machine. The company is refusing to offer refunds for affected machines to allow people to buy another appliance straight away, leaving it open to further criticism.

Instead, Whirlpool suggested owners could still use the machine but with a vastly reduced risk, by only using the cold wash cycle at 20C or less. This means the heating element would not be activated, avoiding the problem that had been identified.

Jeff Noel, vice president of Whirlpool, said: "We know this will cause some concern. We especially understand that the washing machine is so important to family life, and in Christmas holiday season it will be even more of an important matter and, for that, we apologise."

He added that the firm's customer service department was being built up, engineers hired, and delivery and collection capability stepped up for the January start.

The recall only affects UK and Ireland homes at the moment. The products were manufactured in Turkey and Poland.

Is this connected to the recall of Hotpoint and Indesit tumble dryers?

Whirlpool has been embroiled in a four-year scandal over tumble dryer safety. Dangerous appliances under the Hotpoint, Indesit, Creda, Swan and Proline brands were sold in the UK for 11 years from 2004.

They were blamed for a spate of fires after a build up of fluff fell onto the machine's heating element. Whirlpool initially offered to modify affected dryers, only recently turning the offer into a full recall, with partial refund or replacement dryer.

The fire at Grenfell Tower started "in or around" a Hotpoint fridge-freezer in flat 16 on the fourth floor, the public inquiry into the tragedy has heard.

None of these three issues are connected, and Whirlpool said it was conducting the recall of up to 519,000 washing machines because safety was a priority.

Whirlpool has told the regulator, the Office for Product Safety and Standards (OPSS), about the problem and its recall plans.