Zoom Video Communications temporarily shut the account belonging to a group of U.S.-based Chinese activists after they held an event to commemorate the 31st anniversary of China's Tiananmen Square crackdown, the activists said on Thursday.

Humanitarian China said the event they held on May 31 was hosted by a paid account and was joined by over 250 people worldwide via video-conferencing platform Zoom, while more than 4,000 streamed it on social media, many of whom were from China. The account was shut on June 7, they said in a statement.

Zoom confirmed the U.S.-based account had been suspended but had now been reactivated.