NatWest's online services have gone down across the UK with many customers being left locked out of their accounts.
Many have been complaining on social media of their money disappearing, being unable to make payments or even log in.
Customers say the app is having technical problems while others have said they have not been able to get cash out.
The Royal Bank of Scotland, a retail banking subsidiary of the NatWest Group, is also suffering from similar problems.
NatWest's online services have gone down across the UK with many customers being left locked out of their accounts
The bank confirmed on its Twitter account that its mobile app, online banking and telephone services are down
In a statement, the bank said: 'Our mobile app, Online Banking and Telephony Service are currently unavailable and we're working to fix them asap.
'We'll post an update when we have more information.
'In the meantime, please contact us if you need our help.'
A spokesperson had earlier replied to a customer on Twitter: 'We've been made aware of this issue and we're investigating it now as a matter of urgency.
Many have been complaining on social media of their money disappearing, being unable to make payments or even log in
One NatWest user said he went to get money from a cashpoint but was unable to
'We hope to have this resolved as soon as possible.
'We sincerely appreciate your patience at this time and wholeheartedly apologise for any inconvenience.'
One customer wrote: 'Hey NatWest what's going on? I can't make any payments and I can't even logon to my online banking (neither via the app nor via the website!)'
Customers have complained about a variety of problems, saying they cannot make payments or view their accounts
Another said: 'Tried to make a payment to my NatWest account and it's been declined.
'I tried to check my NatWest account and I can't log onto my account. Is the system down?'
MailOnline has contacted NatWest.
