Every registered voter in the Philippines is at risk of identify theft after a massive data breach, it has emerged.

On 27 March a hacker group defaced the Philippines’ Commission on Elections website (COMELEC). A second group then published the country’s voter registration records online in multiple locations.

According to security firm Trend Micro, the database includes passport numbers for 1.3 million overseas Filipino voters, and fingerprint data for 15.8 million people. The entire voter database is 55 million people but it is unclear whether the whole thing has been breached.

It could be the “biggest government related data breach in history”, Trend Micro added. It is bigger than the hacking of the Office of Personnel and Management in the US last year which stole personal information on 20 million government officials.

The report added that “cybercriminals can choose from a wide range of activities to use the information gathered from the data breach to perform acts of extortion,” including bank account access and blackmail.

COMELEC has yet to comment publicly on the latest allegations.