Seoul, Apr 13 (IANS): The Supreme Court here ruled on Thursday that Google must disclose the list of personal information it has shared with third parties, including United States intelligence.

In 2014, four South Korean activists filed a lawsuit against the global tech giant and its local affiliate, Google Korea, demanding to know whether their personal information had been shared with a third party.

Under South Korean law, online service providers must respond to a customer's request to disclose any record of their personal data being shared with a third party, reports Yonhap news agency.

An appeals court had earlier partially sided with the plaintiffs but ruled that Google has the right to reject the demand on issues that can be kept private in accordance with the relevant US laws.

The Supreme Court, however, partially overturned the previous rulings and sent the case back to the Seoul High Court for a retrial.

The highest court said even if personal information was provided to foreign intelligence agencies for probable cause, the service provider must notify the users of such acts when that cause terminates.

The plaintiff alleged Google passed on the private information of its users, including those that live outside the US, to an American government intelligence programme known as PRISM.

PRISM trawls the Internet for email and chat records of anyone who has contacts in the US.

The programme made global headlines after former US intelligence contractor Edward Snowden divulged its existence.

Meanwhile, South Korea's antitrust regulator this week slapped a fine of 42.1 billion won (more than $31.8 million) on Google and its regional arms for unfair business practices aimed at solidifying its dominance in the Korean mobile gaming app market.