Twitter Inc. was only sporadically available to users on Tuesday, suffering technical problems that lasted for several hours.

The company, which has 320 million active users, tweeted that it was aware of the issue and was trying to fix it. The announcement was sent at 03:41 EST. By later in the morning, Twitter appeared to be working again for most users. There was no explanation from the company about what was behind the problem or how it had been resolved.

For a period of time, users said the service was not accessible on desktop computers. Twitter's blog posts, corporate info and most other pages on the Twitter.com website were also inaccessible, displaying the blue error screen.

Twitter's mobile app was partially functioning for some users but its timeline updated new tweets sporadically. Its search function appeared disabled as some hashtags or keyword searches returned no results. Users' profile pages appeared to be accessible from the mobile app.

Third party services, such as the TweetDeck service, also returned a blank page.

Twitter has suffered several service disruptions so far this year. Some users couldn't access it on mobile and the web for about 10 minutes Monday, and the service was disrupted Friday for about 20 minutes.

The Reuters news service cited external monitoring sources as saying the outage appeared to be concentrated in Europe.