Google Inc stopped inviting users to join its new social network less than 48 hours after beginning a limited rollout of the service.
Google senior vice president of engineering Vic Gundotra said that the company had "shut down invite mechanism" for the Google+ service for the night, in a note he posted on Google+ on Wednesday evening.
"Insane demand. We need to do this carefully, and in a controlled way," Gundotra wrote.
Google unveiled Google+ on Tuesday, marking the company's boldest move to take on Facebook, the world's No 1 social networking company. The new Google+ service follows a string of failed attempts by Google to crack the social networking market with products such as Google Buzz and Wave.
A Google spokeswoman declined to say whether Google had resumed inviting people to join Google+ on Thursday or to specify what caused the suspension of invitations.
"We launched Google+ in a Field Trial in order to test the product out and gather more feedback," Google said in an emailed statement.
"As part of the Field Trial, we may open and close Google+ to new users at any time. We're thrilled so many people are interested in trying out a new approach to online sharing."