Twitter boss pledges to tackle abuse on its site

Twitter is to introduce measures to help curb the proliferation of "hate speech" and trolling on its service.

Chief executive Dick Costolo told the Financial Times that he found instances of abuse "horrifying".

Plans could include hiding replies from users who do not have any followers, biography or profile picture.

The news follows the launch of a police inquiry into racist abuse directed at England footballers on Sunday after they missed crucial penalties.

Chelsea's Ashley Cole and Manchester United's Ashley Young were singled out for abusive comments - known as trolling - on Twitter after England's defeat to Italy.

In March, a student was jailed for racially mocking Bolton's Fabrice Muamba on the service after the footballer suffered a cardiac arrest during an FA Cup match.

Mr Costolo told the newspaper that while dealing with these instances was a priority for his service, it was equally important to maintain freedom of speech on the platform.

"The reason we want to allow pseudonyms is there are lots of places in the world where it's the only way you'd be able to speak freely," he is quoted as saying.

"The flip side of that is it also emboldens these trolls... How do you make sure you are both emboldening people to speak politically but making it OK to be on the platform and not endure all this hate speech? It's very frustrating."

Several celebrities and public figures have expressed concern over the volume of abuse on Twitter.

Tory MP Louise Mensch hit out at "immoral and misogynistic" Twitter users who she said had abused her due to her stance on Rupert Murdoch.

Former Nottingham Forest, Liverpool and England footballer Stan Collymore "favourited" - bookmarked - abusive and racist tweets sent to him as a way to highlight the problem.

Joshua Cryer, 21, was given a two-year community order after racially abusing Mr Collymore on Twitter.