Singapore halted the use of Zoom Video Communications Inc.’s video-conferencing application for home-based school education following reports of hackers breaching some of the sessions and posting obscene images.

“These are very serious incidents,” Aaron Loh, divisional director of the educational technology division at the city-state’s Ministry of Education, said in an emailed reply to Bloomberg News queries. “MOE is currently investigating both breaches and will lodge a police report if warranted,” he said.

The action comes as harassers breached some e-learning modules and displayed obscene images in the sessions, the Straits Times reported on Thursday. Zoom is focused on ramping up the security of its application to win back trust and clients it has lost due to privacy concerns, Chief Executive Officer Eric Yuan said in an interview with Bloomberg TV this week.

On Wednesday, Taiwan instituted a ban on the use of Zoom for official government communications and remote meetings, joining Elon Musk’s Tesla Inc. and SpaceX as well as the New York City Department of Education in prohibiting the app. Cybersecurity and privacy concerns were at the root of their actions, and Singapore’s experience with insecure video-conferencing lessons adds to the company’s unhappy record.

“We recently changed the default settings for education users enrolled in our K-12 program to enable virtual waiting rooms and ensure teachers are the only ones who can share content in class,” a Zoom spokesperson said. The company is also adding a new “Security” icon to the app’s toolbar for all users, giving quicker access to security features.