BANGKOK, June 13 -- Millions of bank customers across Thailand are bracing for service disruptions as three of the country's biggest banks prepare for extensive system maintenance in the days ahead.

The Nation reported that Krungthai Bank, the Government Savings Bank (GSB) and Siam Commercial Bank (SCB) have all announced scheduled outages that will temporarily take down a wide range of core banking functions - including mobile apps, ATM access, and credit card transactions.

Customers have been urged to plan ahead, with services such as bill payments, international transfers, and even notifications on messaging platforms like LINE expected to be interrupted.

Krungthai Bank is implementing two separate maintenance periods. The first - a...