Facebook Inc. said Friday that personal data from 29 million accounts were accessed in a security breach that occurred in September, fewer than the 50 million originally thought.

The social media giant said in a statement that of the 29 million people, 15 million had their names and contact details accessed while 14 million people had that information as well as other details, including their birthdays and work, obtained.

An additional 1 million users had their access tokens stolen but no information was accessed.

The attack did not include the company's related services including Messenger, WhatsApp and the photo-sharing site Instagram.

Facebook is struggling with security issues after saying in April data on up to 87 million users may have been improperly shared with the political consulting firm Cambridge Analytica, which worked for the 2016 U.S. presidential election campaign of Donald Trump.

Late last month, the company said it discovered a security issue that could have let attackers take over almost 50 million user accounts.

Users can check whether they were affected by visiting the "Help Center" on Facebook's website. The company will also send customized messages to those affected to explain the information accessed as well as some recommended protective steps.

Attackers had found a flaw in Facebook's "View As" feature that lets people see how their profiles look to others. This vulnerability allowed them to steal digital keys, which then helped them to take over people's accounts. Facebook has said it has fixed the security issue.