According to complaints tracker website Downdetector, more than 310 people were unable to use online banking when it crashed around midday.
The issues, which have since been fixed, started around 12.30pm, with 63% reporting issues with online banking, 27% with online login troubles, and 10% with mobile banking problems.
The problems were resolved at around 2:20pm, Natwest said.
A spokesperson for the bank said: “Our NatWest Online Banking is now working as normal. We apologise for the inconvenience caused. No customer will be left out of pocket as a result.”
The area most affected area was London, with issues reported in other cities including Manchester, Birmingham and Bristol too.
Customers took to Twitter to complain about their issues logging in and making payments during the two-hour outage.
Many sent screenshots of the NatWest login webpage saying “site can’t be reached”.
One customer said: “Just saying site cannot be reached when clicking the login button.”
Another said: “Why is the online banking down? Trying to make payments.”
While one customer said nothing happens when they login – and then the “screen times out”.
There’s no automatic right to compensation if there’s a service failure at your bank.
But you could get money back in some circumstances, depending on how an outage has affected you.
It is worth gathering evidence of your problems so you can make a formal complaint to NatWest.
Try to make a note of when you were unable to access the website or app, plus any costs you incurred as a result.
If your credit rating has been affected by a service outage, because you got a late payment fee after being unable to make a transaction, for example, you should also keep a record of this.
A NatWest spokesperson said: “We are aware that some customers are experiencing difficulties accessing NatWest Online Banking.
“We apologise to customers for the inconvenience and we’re working to resolve this as quickly as possible. Our customers can still access mobile, video and telephone banking, or visit a branch.”
It comes as HSBC customers also reported issues logging onto their accounts.
Problems were first reported at around 9.30am, but now the issues have been resolved.
They’re not the only two banks to have suffered website and app crashes recently.
Lloyds Bank, Halifax and Bank of Scotland all went down earlier this month, locking thousands of customers out of their accounts.
How can I check if NatWest is down?
NatWest is part of the NatWest Banking Group and runs online, telephone and app banking services.
You can check the status of NatWest’s mobile banking, online banking and websites using its service status webpage.
Social media can also be a good place to look, and each bank has its own pages.
Downdetector highlights outages for both NatWest too.
If you can’t get online but need to access your money, You can find your nearest NatWest branch using its branch finder tool.
You can also ring up the bank or visit an ATM too.