The G-Cloud programme will cost £4.93m, but save £340m, according to Cabinet Office minister Francis Maude.
The figure includes the cost of setting up and maintaining the CloudStore G-Cloud app store, Maude said in response to written questions by Labour MP Michael Dugher on Monday. No information was available from the Cabinet Office at the time of writing about the length of time the costs figures covered.
Maude said that government datacentre numbers would be published in the ICT Strategy annual update report, which is "due shortly".
As part of government cloud computing plans, some public data will be hosted on Amazon, Google, and Microsoft servers, G-Cloud assistant programme director Eleanor Stewart said in a blog post on Friday. The government already uses some Amazon, Google and Microsoft cloud services, said Stewart.
"'Cloud computing' does not necessarily mean US hosting. The UK Government CloudStore contains 1,700+ cloud services from UK and international providers," said Stewart.
"The UK Government may well use Amazon's, Google's or Microsoft's servers, and already does in some cases, but it will not use them for data processing of workloads that are inappropriate for their security accreditation status in respect of legal compliance or our national security policies."
Denial of service attacks on government websites by groups such as Anonymous are "at one end of the scale" when it comes to security threats — the government "don't really care" if some websites get taken down, said Stewart.
"The kinds of data we deal with and the information systems that carry those workloads range from, on one end of the scale websites like this that have near zero information-security requirements and we don't really care if it is up 24/7 or not... [to]... information which could if compromised cause death or injury, prejudice criminal proceedings, have national security implications, or adversely affect international diplomacy," said Stewart.