Image caption The company apologised to customers about the fault

Worried owners of Hotpoint and Indesit washing machines struggled for 24 hours to access a recall website to check whether their machine is a fire risk.

Half a million appliances need to be fixed or replaced as their door locking system can overheat.

But manufacturer Whirlpool's model checker website was blighted by technical difficulties.

The company has apologised for the safety issue and the IT fault. The site should now be working.

"We are truly sorry for the technical issues customers have been experiencing on our website. One of our third-party service providers suffered an issue which affected our recall website," a Whirlpool spokesman said.

"We've been working with them through the night, and have built a new online system to fix this."

An alternative phone line has been set up - on 0800 316 1442 - although, as it connected to the same system, some customers had difficulties accessing that too. The company had still taken 17,000 during morning.

Media playback is unsupported on your device Media caption Whirlpool boss apologises for recalling machines at Christmas

Angry customers include Jolene, from Leicester, who said she believed she had one of the affected machines.

"I have a daughter with disabilities and kidney issues causing incontinence, so our machine is in daily use," she said.

"Every time I get the message saying the number you have called is unobtainable, making it impossible to contact them to report the issue, and with having a vulnerable child, and having disabilities myself is leaving us at risk."

What is the safety problem?

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

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

Steve Smithson, from Romford in 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.

The engineer said that this was the fourth one he'd done in less than a week. He said we were quite lucky, as another person had the front of their machine almost melt due to the heat."

Media playback is unsupported on your device Media caption Smoke was coming from my washing machine

For those who eventually discover that their machine is one of those at risk of catching fire, the process of fixing or replacing it will begin in January. It should be unplugged until fixed. The company would not be drawn on when everyone's case will be dealt with.

As a result, owners may have to cope without their washing machine for months. The company is refusing to offer refunds and anyone who buys an alternative will not be able to charge Whirlpool for the cost.

The fix must also be carried out by a Whirlpool engineer, so owners should not attempt to hire their own engineer to get the work done quicker.

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 chain of events that can lead to the door locking system overheating.

'Never-ending saga'

Whirlpool has already 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.

Whirlpool has just agreed a settlement with residents who were left homeless when one of its faulty tumble dryers caused a large tower block fire at Shepherd's Bush in London.

Rachel Reeves MP, who chaired the Business Committee in the last Parliament, which investigated the Whirlpool saga, said: "Whirlpool has yet again betrayed the confidence of its customers and left them fearing they have potentially dangerous washing machines in their homes.

"Whirlpool must act immediately to solve this seemingly never-ending saga with its products. If they cannot swiftly fix or replace machines with potential problems, they should offer affected customers a full refund."

The affected washing machine models are:

FML 742P UK Hotpoint, WMAOD 743G UK Hotpoint, WMAOD 743P UK Hotpoint, WMAQB 721P UK.M Hotpoint, WMAQC 641P UK.M Hotpoint, WMAQC 741G UK Hotpoint, WMAQC 741P UK Hotpoint, WMAQC 741P UK.M Hotpoint, WMAQF 621G UK Hotpoint, WMAQF 621P UK Hotpoint, WMAQF 641 P UK.M Hotpoint, WMAQF 721G UK Hotpoint, WMAQF 721P UK.M Hotpoint, WMAQL 621G UK Hotpoint, WMBF 742G UK Hotpoint, WMBF 742K UK Hotpoint, WMBF 742P UK Hotpoint, WMBF 742P UK.M Hotpoint, WMBF 763P UK Hotpoint, WMEF 722 BC UK Hotpoint, WMEF 742 P UK Hotpoint, WMEUF 722P UK Hotpoint, WMEUF 743G UK Hotpoint, WMEUF 743P UK Hotpoint, WMFG 741P UK Hotpoint, WMFG 741P UK.M Hotpoint, WMFUG 742 P UK.M Hotpoint, WMFUG 742G UK Hotpoint, WMFUG 742P UK Hotpoint, WMFUG 842P UK.M Hotpoint, WMJLF 842P UK Hotpoint, WMJLL 742P UK Hotpoint, WMSAQG 621P UK Hotpoint, WMXTF 742G UK Hotpoint, WMXTF 742K UK Hotpoint, WMXTF 742P UK Hotpoint, WMXTF 742P UK.M Hotpoint, WMXTF 842P UK.M Hotpoint, WMYL 7151PS UK Hotpoint. XWA 81252X K UK Indesit, XWA 81252X W UK Indesit, XWD 71452X K UK Indesit 171418.