Privacy campaigners condemned Twitter yesterday for allowing businesses to buy access to its archive of millions of tweets.
About seven million people in Britain use the social networking website to post short messages to ‘followers’.
Most believe their tweets are unavailable to those outside their chosen network after a week because that is when they can no longer be searched for on the site.
More than 1,000 companies have joined a waiting list to use the data, compiled from around 250 million Tweets a day
But Twitter has archived every tweet – there are about 250 million a day – and has agreed a deal allowing the UK-based company Datasift to trawl through all those posted since January 2010.
The company will use the information to help firms with marketing campaigns and target influential users.
The licensing deal is part of Twitter’s plan to generate revenue from its service, which is free to its estimated 300 million users worldwide.
But the move has alarmed privacy campaigners, with the online rights group the Electronic Frontier Foundation describing it as ‘creepy’.
Nick Pickles, director of the Big Brother Watch campaign group, said: ‘People may consider tweets to be personal property but this deal makes clear they are not. Our personal posts on social media are yet another way for advertisements to be better targeted and that’s a very lucrative industry.
‘It’s clear that if you’re not paying for a service, you are not the customer – you’re the product.’
Datasift charges companies up to £10,000 a month to analyse tweets posted each day for anything said about their products and services.
It claims to have a waiting list of up to 1,000 clients wanting to riffle through the huge Twitter archive for data that could help them target advertising and develop marketing campaigns. Private accounts and tweets that have been deleted will not be indexed by Datasift.
Gus Hosein, of the watchdog group Privacy International, said: ‘People have used Twitter to communicate with friends and networks in the belief that their tweets will quickly disappear into the ether.
‘The fact that two years’ worth of tweets can now be mined for information and the resulting “insights” sold to businesses is a radical shift in the wrong direction.
‘Twitter has turned a social network that was meant to promote global conversation into a vast market-research enterprise with unwilling, unpaid participants.’
Justin Basini, of the data privacy company Allow, said: 'Marketers will stop at nothing to get hold of your data. This move shows all those throwaway tweets have suddenly become a rich new revenue stream for Twitter.
'It has taken a stream of consciousness, analysed it, bottled it and sold it for a profit. And the worst thing is, you never knew it was going to happen.'
Datasift searches through 250 million Tweets a day. It is one of two companies so far offered access to Twitter's 'firehose' - all the information that flows through the site Graham Cluley from security firm Sophos said, 'The news will surprise some. Twitter has found another way to monetise its service, having partnered with a firm which will make it simple for market researchers working for big companies to search and analyse the last two years of your Twitter updates.
'You thought that tweets you posted months ago had vanished, or were simply hidden away so deeply and awkwardly on the Twitter website that they would be too difficult to uncover? Think again.'
But Datasift’s Tim Barker said: ‘It should come as no surprise to users that their tweets are archived – they can see every update they have ever sent on their timeline.
‘Twitter was always created to be a public social network.’
The row comes amid privacy concerns on other social networks.
Facebook has been criticised after admitting it can read the text messages of those who use the service on their mobile phones.
And the web giant Google has also come under fire for collecting data about internet users.
Datasift is one of two companies granted access to Twitter's 'firehose' - the full amount of data streaming through the site.
'DataSift goes beyond what many social media monitoring companies do,' says founder Nick Halstead.
'Instead of just searching on keywords such as 'Nike', DataSift can search on all the people, products, and links associated with the company, then slice and dice the data for different departments such as marketing, product and the like.'