Twitter's service had problems on Monday for over six hours with some users complaining the service was slow, while others could not access it at all.
The service interruptions came after Twitter claimed that there were 1.1 million inauguration-related messages on its service during the inauguration ceremony of U.S. President Barack Obama.
Some users were experiencing issues accessing Twitter, the company said in a message. Twitter's engineers then worked to resolve the problem, it added.
A company spokeswoman did not comment on what caused the interruptions. "Unfortunately, we don't have anything to share beyond what is on the status blog," she said via email on Monday.
There was speculation that Twitter went down as a result of a large number of Twitter messages during Obama's inauguration and related events. During the ceremony, there were 1.1 million inauguration-related messages on its service, with 27,795 per minute at the peak, Twitter said.
A notice on the company's developer section indicated late Monday that the service was still having disruptions in a number of areas such as timeline, favorites and friends.
Later in the evening, Twitter was reporting that its help center was down. "We will send an update when the issues have been resolved," Twitter user support said in a message. Earlier, it reported that profile photo upload was unavailable. "Hold tight, we hope to have it back soon," it said.
Twitter also had interruptions in its service last week. It reported that it was experiencing intermittent problems with Twitter's rendering of pages. The issue was resolved, it said later in the day.
Twitter reported around midnight U.S. Eastern Time that the incident on Monday had been resolved, but did not provide information on what had caused the interruptions.