Slack says it mistakenly deactivated accounts for some of the users this week

Slack says it mistakenly deactivated accounts for some of the users of its work-focused messaging service this week as it implemented a system update to comply with U.S. economic sanctions and trade embargoes.

In its blog Friday, Slack said it had “inadvertently deactivated a number of accounts,” adding access has been restored to most. It declined to say Saturday how many users were affected.

Slack says it will soon begin blocking access to users with an internet connection associated with a country under U.S. sanctions. Those include Iran, North Korea, Cuba and Syria.

The disruption prompted Slack users to complain on Twitter, including ones in Canada and Belgium who said they had merely visited Iran. Slack says it will block users visiting a sanctioned country, but it won’t deactivate their accounts.