Twitter will licence the data to other companies, but Datasift is the first to take the microblogging service up on the offer of two-years’ worth of data.

Until now, companies have only had access to tweets dating back 30 days while users can only search for tweets produced in the last seven days.

Datasift’s new service, Historics, aggregates and filters the data it collects from all these tweets and delivers it into social media monitoring, business intelligence and CRM applications. Each tweet is analysed for sentiment, topic, location and social media influence.

Datasift CEO Rob Bailey said: “The sheer volume of data being produced by Twitter represents a huge challenge for companies trying to extract insights from past events.”

Historics is available as a limited release to existing customers and is scheduled to become generally available in April. Datasift says it already has almost a thousand companies – including 100 of the Fortune 500 companies – on a waiting list.

But while firms clearly like the idea of accessing all this data, and for Twitter its a way to monetise its service, privacy groups have responded warily to the development.

Privacy International’s executive director Gus Hosein told the BBC: “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 real-time global conversation into a vast market research enterprise with unwilling, unpaid participants.”