"Shambolic" IT services at government departments are calling into question the government's decision to hand more IT contracts to smaller providers.

According to the Financial Times business secretary Vince Cable and energy secretary Ed Davey have told prime minister David Cameron that their departments had suffered intermittent email and poor internet and network connections since they started migrating to new computer systems in early May.

The switch from big IT outsourcers to smaller providers has been trumpeted by the Cabinet Office as a way to save money, while at the same time creating a fairer market for SMEs in the public sector.

The business and energy departments share a computer system which was previously supported by Fujitsu Systems. The new arrangement sees the system supported by several smaller suppliers on shorter-term contracts.

After the problems his department experienced, the FT says Cable has urged cabinet colleagues to refrain from signing new IT contracts for their own departments as "lessons could [first] be learnt" from his department's service issues.

One government official quoted by the FT says, "Getting more SMEs in was an idealistic Tory policy in 2011 to shake up Whitehall. But in effect they are not necessarily the best fit for this sort of task."

Another said "it has been shambolic", with their department suffering lost data, slow connections, screen freezes and intermittent email.

The energy department confirmed it had suffered some disruption from the new system, but that most people had been able to continue with their work. An official told the FT, "It's been a very bumpy ride for the last few weeks but everyone has worked through it and carried on delivering."

The type of IT problems seen in Whitehall were also faced by the Houses of Parliament earlier this year. The IT department for Parliament blamed IT problems on work that was carried out by one of its IT contractors. Parliament is testing and rolling out the cloud-based Office 365 productivity suite to users.