Data of some 6 million taxpayers in the world's fourth-most populous nation, Indonesia, including of outgoing President Joko Widodo, has been allegedly leaked and sold, said a media report on Thursday.

Millions of taxpayer identification numbers have been “sold for $10,000 on the Breach Forum website” by an account claiming to belong to a hacker known as Bjorka, Jakarta Globe reported.

It added that the sale was completed on Wednesday.

The leaked data includes national ID numbers, emails, addresses, phone numbers, and other personal information, it said.

The Directorate General of Taxes of the Southeastern Asian nation, home to around 275 million people, is investigating the alleged breach.

Quoting Ethical Hacker Indonesia founder Teguh Aprianto, the report said: “The leaked data includes personal information belonging to President Joko Widodo, as well as his sons Gibran Rakabuming Raka and Kaesang Pangarep.”