The national pension system has been hacked, leading to 1.25 million cases of personal data being leaked, the Japan Pension Service announced Monday.

In a scandal reminiscent of the nation's botched handling of pension records about a decade ago, people's pension IDs, names, addresses and birth dates have been stolen through illicit accesses to fund workers' personal computers, fund officials said.

The data were leaked when agency employees opened an attached file in their email containing a virus.