It said the flaw allowed "name, email address, occupation, and age" to be exposed to third-party developers, even if accounts had been set to private.

The bug, discovered "recently", was introduced to the network in November.

In October, Google decided to close Google+ to the public after finding data on 500,000 of its users had been exposed.

As a result of this latest find, it said, the closedown had been brought forward.

"With the discovery of this new bug, we have decided to expedite the shutdown of all Google+ APIs [application programming interfaces]; this will occur within the next 90 days," wrote David Thacker, head of product management for G Suite, Google's range of apps offered to businesses.

"In addition, we have also decided to accelerate the sun-setting of consumer Google+ from August 2019 to April 2019.

"While we recognise there are implications for developers, we want to ensure the protection of our users."

Mr Thacker added that the problem was discovered by Google staff via routine testing, and that there was no evidence it had been exploited by bad actors.

Google+ has long been the butt of jokes for being a failed social network that few people used.

Sundar Pichai will be quizzed by Congress on Tuesday

However, October's admission of exposed data was poorly received after it was revealed the company knew about the issue in March. Internal memos suggested it initially chose not to tell the public about the issue, fearing the possibility of regulatory scrutiny.

This latest admission comes a day before Google's chief executive Sundar Pichai appears in Washington to face a Congressional committee.

The hearing is to discuss concerns of political bias across Google's products, but will almost certainly stray into other areas of the company's work, such as its ambitions in China, and complaints about how the company treats its female employees.