Facebook Inc said on Thursday some users were facing issues while sending messages on Messenger, Instagram and its office collaboration service Workplace.
"We're working to get things back to normal as quickly as possible," a company spokesperson said.
Outage tracking website Downdetector.com showed that there are more than 1,800 incidents of people reporting issues with Messenger and 350 reports on Instagram.
On Wednesday, the U.S. Federal Trade Commission and nearly every U.S. state filed lawsuits against Facebook, saying it used a "buy or bury" strategy to snap up rivals and keep smaller competitors at bay.
The FTC had said in a statement that it would seek an injunction that "could, among other things: require divestitures of assets, including Instagram and WhatsApp."
(Reporting by Ayanti Bera in Bengaluru; Editing by Amy Caren Daniel)