South Korean President Lee Jae Myung ordered a thorough investigation on Sunday into recent personal data leaks at banks, finance companies and public agencies, Reuters reported. Seoul’s presidential office said the probe must cover response measures as well.

Financial Services Commission chairman Lee Eog-weon held an emergency meeting on Sunday with banks, regulators and affected institutions. He warned the sector to respond with the highest level of vigilance, the FSC said in a statement.

The meeting followed an earlier round of talks on Friday. Yonhap news agency reported that Hana Bank and Woori Bank had also suffered breaches, after Shinhan Bank and KB Kookmin Bank reported cyberattacks.

Regulators said on-site investigations began after Shinhan Bank reported a breach on September 30. The FSC’s chairman said authorities could not rule out that artificial intelligence was used in the attacks. He called for an “AI attacks defended by AI” approach and wider upgrades to financial cybersecurity.

The regulator has directed banks to run full security inspections, tighten access controls and cut unnecessary external system access. The banks could not be reached for comment on Sunday.