Credit card company American Express is experiencing an outage in Europe.

Users report transactions declining, and being unable to pay off debt.

"We are currently experiencing multiple technical issues impacting our servicing and payment systems," American Express said on Twitter.

"Thank you for your patience while we work to resolve these. If you are trying to make a payment, please do so by bank transfer – sort code & account information is on your statement."

The company did not provide a reason for the multi-hour outage.

Amex operates a data center adjacent to its main European offices in Brighton, UK.