Chase Bank said it had resolved an issue that had prevented its customers from using a majority of its ATMs on Sunday.

"We have resolved the issue that prevented customers from using our ATMs today. They could still use their debit cards on purchases and other bank ATMs," a Chase Bank spokesperson said.

A message posted on the U.S. company's website earlier said it was working to restore its ATMs and bring them back online, but it appeared later to have been removed. The outage affected a majority of Chase Bank's network of more than 16,000 ATMs.

The outage was due to an internal technology-related issue, a source said on condition of anonymity.

Downdetector, which tracks outages by collating status reports from several sources including users, said there were reports of around 900 outages at its peak at 4 p.m. EDT, but the reports had now come down to around 300.