Chinese/Japanese/Korean characters do not display when using Greek locale

When running a Qt application when Windows XP's locale is set to Greek, Chinese/Japanese/Korean characters appear only as thick vertical lines, indicating that the character could not be found.

However, these exact same characters will successfully display in the same application when the locale is English.

Furthermore, in Greek Locale, although a Qt app will not display the characters, other applications/text editors will (Firefox, MS Notepad, jEdit, MS Visual Studio, etc.).

This would indicate that the problem is not due to a missing font in the system.