Twitter said Thursday some users could not access the messaging service amid reports of an outage in some parts of the world.
"We are currently investigating issues people are having accessing Twitter," a spokesperson said in an email. "We'll keep you updated on what's happening."
The monitoring website DownDetector showed a series of outage reports starting at 1846 GMT, concentrated in Europe, North America and Japan.
Users trying to access Twitter saw a message saying "Something is technically wrong."
The outage occurred as President Donald Trump convened what he called a "social media summit" where conservative critics of Silicon Valley were expected to voice grievances.
Trump, who has more than 60 million followers on Twitter and uses the platform extensively, nonetheless has complained that it suppresses some political viewpoints.
Earlier this month Facebook experienced an outage of several hours due to what the company said was a bug triggered by a maintenance operation.