The social messaging service's co-founder Jack Dorsey will take over as interim chief on 1 July and stay until a replacement can be found.

Mr Costolo had been under pressure from investors unhappy with the firm's user growth.

In a statement, he said he was "tremendously proud of the Twitter team".
Twitter said that its board had formed a committee to undertake the task of finding a successor.

Following the announcement, shares in the company jumped by more than 7% in trading after US markets had closed.

In announcing his resignation, Mr Costolo said in a statement: "I am tremendously proud of the Twitter team and all that the team has accomplished together during my six years with the company.

On a conference call to discuss the move, he added that he had decided to go now because he felt the continued scrutiny if he remained would be a "distraction" and of "no help to the company".

Questioned on what the board was looking for in its next chief executive, Mr Dorsey said the search team would take as long as necessary, the candidate could come from inside or outside the company but added the one criteria they knew for sure: he or she should be a Twitter user.

Mr Dorsey said the most important attribute was that they "really use and love the product in every single way".