The web giant Amazon has cornered more than a third of the lucrative UK market in "cloud" services that store and process government-held information, including sensitive biometric details and tax records, figures leaked to The Telegraph suggest.

The details come as Amazon is due to announce financial results this week that will highlight how important its provision of such services, through an offshoot known as Amazon Web Services, are to the profitability of a company much better known for its online superstore.

In the first six months of this year, for example, AWS made $4.3bn (£3.33bn) on global revenues of $16bn, while the more famous part of Amazon made only $3.1bn on global revenues of $107bn.

AWS profits have been driven by rocketing demand from customers paying to store data or buy processing power on computers owned and run by Amazon. AWS revenues from UK government contracts relating to cloud services known as “Infrastructure as a Service” (IaaS) and “Platform as a Service” (PaaS) grew by more than 50pc last year, the leaked figures suggest.

Such is the pace of the growth that some critics claim that the UK Government’s reliance on AWS poses a systemic risk, should AWS servers crash.