An email error by an employee of Australian immigration department accidentally sent the passport numbers, visa details and other personal identifiers of the heads of government attending the G20 Leaders' Summit in Brisbane last November to the organisers of the Asian Cup football tournament, the Guardian reported.
Besides Modi, US President Barack Obama, Russian President Vladimir Putin, German Chancellor Angela Merkel, Chinese President Xi Jinping, Japanese Prime Minister Shinzo Abe, Indonesian President Joko Widodo and British Prime Minister David Cameron were among those whose details were exposed, the report said.
The Australian privacy commissioner was contacted by the director of the visa services division of Australia's Department of Immigration and Border Protection to inform them of the data breach on November 7, 2014, and seek urgent advice.
But the newspaper claimed that it was not considered necessary to inform the world leaders of the privacy breach.
In the email, obtained under Australia's freedom of information laws, the breach is attributed to an employee who mistakenly emailed a member of the local organising committee of the Asian Cup held in Australia in January with the personal information.
"The personal information which has been breached is the name, date of birth, title, position nationality, passport number, visa grant number and visa subclass held relating to 31 international leaders (ie prime ministers, presidents and their equivalents) attending the G20 leaders summit," the officer wrote.
"The cause of the breach was human error. (Redacted) failed to check that the autofill function in Microsoft Outlook had entered the correct person's details into the email 'To' field. This led to the email being sent to the wrong person.
"The matter was brought to my attention directly by (redacted) immediately after receiving an email from (the recipient) informing them that they had sent the email to the wrong person. The risk remains only to the extent of human error, but there was nothing systemic or institutional about the breach," the officer wrote.
The immigration officer then recommended that the world leaders not be made aware of the breach of their personal information."Given that the risks of the breach are considered very low and the actions that have been taken to limit the further distribution of the email, I do not consider it necessary to notify the clients of the breach," the officer wrote.
The recommendation not to disclose the breach to the world leaders may be at odds with privacy law in some of their countries.
Australia's deputy opposition leader, Tanya Plibersek, called on Prime Minister Tony Abbott, to explain why the world leaders were not notified of the breach.
Australia's immigration department was also responsible for the country's largest ever data breach by a government agency.
In February 2014, the 'Guardian' had reported the agency had inadvertently disclosed the personal details of almost 10,000 people in detention many of whom were asylum seekers in a public file on its website.