April 18 (UPI) -- Social giant Facebook said it "unintentionally" uploaded more than a million user email contacts to the site in mid-2016, due to a problem it took nearly three years to find.
The company announced the issue Wednesday, saying users were allowed to upload their email contacts to Facebook, presumably to find their friends' pages easier. Changes in May 2016, however, allowed the contact lists of about 1.5 million users to be uploaded to Facebook without users' knowledge.
"When we looked into the steps people were going through to verify their accounts, we found that in some cases people's email contacts were also unintentionally uploaded to Facebook when they created their account," a Facebook spokesman said.
The spokesman said it took almost three years for Facebook to find the problem, which affects users who signed up since the change was made. It was discovered when new users were asked to enter email passwords to verify their identities. That linked the email to the Facebook account, prompting a message that said it would "import" contacts to the network without asking permission.
The company said although the lists were uploaded by mistake, they weren't shared with anyone outside Facebook and will be deleted, the spokesman said.
"We're fixing the underlying issue and are notifying people whose contacts were imported," he said.
The issue is the latest to make trouble for Facebook. The company is still feeling effects from the Cambridge Analytica scandal and other privacy concerns.
Facebook has also made multiple efforts recently to weed out hate speech, violent content and political manipulation. Thursday, it permanently banned several far-right organizations and individuals under its "dangerous individuals and organizations" policy.
In all, 12 accounts were banned for violating the policy -- including the British National party, the English Defense League and Britain First.
"Individuals and organizations who spread hate, or attack or call for the exclusion of others on the basis of who they are, have no place on Facebook," the company said. "Under our dangerous individuals and organizations policy, we ban those who proclaim a violent or hateful mission or are engaged in acts of hate or violence."