Sumitomo Mitsui Banking Corporation (SMBC) said Tuesday that a system failure has occurred, making automated teller machines at some branches in the Kansai region of western Japan unavailable.

The cause of the failure is under investigation, and there is no timeline yet for restoring the system, the Japanese bank said.

The failure started around 1:20 a.m. Tuesday, affecting ATMs at about 50 branches and sub-branches in prefectures including Hyogo and Osaka. Internet banking is also unavailable for accounts at the impacted locations.

No cyberattack has been confirmed at this time, SMBC said.