Customers of Singapore’s DBS Group Holdings Ltd. and Citigroup Inc. were unable to access banking facilities for several hours after an issue at a data center used by the lenders.

Payment services were disrupted for several hours on Saturday, and the Monetary Authority of Singapore said it was informed of the matter by the banks in the afternoon. Singapore Telecommunications Ltd. said its engineers verified its networks were working as normal after customers had problems accessing social media platforms and banking services.

Some of the banks’ customers who were outside Singapore said on Facebook they were unable to use credit cards issued by the lenders or carry out online transactions.

“Preliminary investigations indicate that the service disruptions were caused by an issue at a common data centre that is used by the banks,” the MAS said in a statement. “MAS has been following up closely with the banks, as they work towards a full resumption of their services, and provide timely communications and support to affected customers.”

The latest disruption follows delays experienced by DBS customers last month in processing transactions on one of its payment services. In May, officials imposed higher capital requirements on DBS, Singapore’s largest lender, following glitches with its online services that the regulator called “unacceptable.”

“Please be assured that our systems are uncompromised, and your monies and deposits remain safe,” the bank said on its Facebook page on Saturday, adding that the data center was used by various organizations.

READ: DBS Digital Payments Back to Normal After Tuesday Disruption