Update 4.30pm 26 Mar 2016: The EHIC website is now working
Travellers are unable to apply for EHIC cards as the website has crashed, but don't be tempted to go via a shyster site.
The NHS has said it is working as quickly as possible to fix the site, and is hoping to have it back up and running this afternoon.
A spokesman confirmed some other NHS systems are being affected, but said it is unrelated to the NHS earlier this month and is due to technical difficulties.
The free European Health Insurance Card (EHIC) entitles you to free or discounted medical treatment at state-run hospitals and GPs in any European Union country, plus Iceland, Liechtenstein, Norway and Switzerland, and so is a must-have for any traveller. See our EHIC guide for more information.
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What should I do if I need to get one?
It's not clear how quickly the problem will be fixed, and we'll update as soon as we know.
The website currently says: "NHS Business Services Authority are sorry for the continuing disruption to their services which includes the EHIC application form. NHSBSA are hoping to resolve the issue as soon as possible but until then contact centre staff will, regrettably, be unable to assist with requests that require system access. Thank you for your patience."
A spokesman said there has been problems over the last 36 hours caused by a power failure which resulted in some equipment faults.
She added: "Our systems are being restored and tested now and we are hoping that these will be fully operational by close of play today. No personal details or data has been compromised - this is an IT loss of service."
In the meantime, don't be tempted to go via a shyster site which will try to charge you £20 or more for the free card. They dress up like legitimate sites, using search optimisation tricks to appear high on Google but you should never pay for an EHIC card, see our 60 Seconds on Copycat Sites guide for more information.
Also, always remember the EHIC isn't a substitute for travel insurance. You should always book travel insurance as soon as you've booked your trip, see our Cheap Travel Insurance guide for more.
If you're due to travel soon and haven't already applied for your EHIC, it generally takes about seven to 10 days to arrive so apply as soon as the site is working again.
We'll update this story as soon as we have more information.