by: Lee Moran | dailymail.co.uk

It was credited with fanning the flames of unrest across the Arab world as citizens took to the streets in protest and decades-old regimes fell.

It helped co-ordinate the Occupy movement that swept across the globe, and was blamed for playing a key part in last year's devastating riots in London.

But Twitter's role as the modern bastion of free speech is now at risk as the firm moves forward with an aggressive expansion strategy to grow from 100 million to 1 billion regular users.