The UK Office for National Statistics has admitted that this year's publication of the national accounts will be incomplete due to the introduction of new computer systems.

The ONS publishes the National Accounts Blue Book every year, with detailed estimates of the UK's gross national product, income and expenditure.

But Chancellor Gordon Brown's Budget statement Wednesday was followed by publication of a substantially slimmed down Blue Book for 2007.

An ONS spokesperson said: "We intend to introduce a new computer system later this year in time for our annual publication, Blue Book, in 2008. We have suspended part of Blue Book 2007 in order to do testing."

The ONS is overhauling the systems used to produce the National Accounts, as part of a wider modernisation of statistical systems that saw the agency extend its contract with IT partner Xansa in June 2006, with the contract expected to be worth a minimum £6 million over two years.

An ONS paper about the National Accounts overhaul says: "ONS currently has a wide range of statistical and technical legacy systems that are outdated, high risk and inefficient."

But it adds: "It has proved necessary to free resources from other activities in order to ensure this transition is managed as smoothly as possible with a complete range of analysis."

The 2007 Blue Book has therefore been "designated a transition Blue Book with a number of regular outputs temporarily postponed", said the document.

This year's Blue Book will omit the publication's usual annual benchmark survey data, including the Annual Business Inquiry and estimates from HM Revenue and Customs of income.

Postponing the benchmarking would "create some temporary additional uncertainty about the path of the economy until Blue Book 2008," the document admits.

The modernisation programme is aimed at eventually creating a shared corporate data repository, dubbed the Central ONS Repository for Data (Cord) to hold all the agency's statistical sources in a common environment. The overhaul is also expected to allow the standardisation of statistical methods, systems, processes and technology used to produce key ONS reports.

The modernisation programme includes a re-engineering of business processes, in a move designed to reduce statistical risk and improve efficiency and effectiveness.