Departments will adopt increasingly radical and innovative ways to become more sustainable, ministers have promised.

Treasury minister Ian Pearson has made the promise as figures for 2008/09 are published showing that departments are largely on target to meet their targets of reducing carbon emissions by 12.5 per cent by March 2011.

The Sustainable Development Commission (SDC) watchdog has reviewed the data and commended departments and agencies for their overall improvement, but has also criticised some practices, such as the dropping of poorly performing organisations from the figures.

The overall star rating awarded to the government by the SDC remains at four out of five, despite 81 per cent of primary operational targets being met this year in comparison with 78 per cent last.

Pearson said the figures "demonstrate the strong commitment and progress being made across Whitehall to address the crucial matter of reducing the environmental impact of government’s day-to-day business operations".

The SDC has called again for the government to take a bolder approach to sustainability; Pearson has responded by insisting that the government is "dedicated to encouraging more radical and innovative approaches to tackling negative impacts on the environment".

The Department for the Environment, Food and Rural Affairs is working on a new set of targets, to be published next year, to replace the existing measures of estate and procurement on which today's figures are based.

SDC vice-chairwoman Rebecca Willis has praised the "considerable efforts" of departments in improving performance against road transport, water, waste and recycling targets, but warned the government that "the next task for government is to get to grips with its supply chain, and to look at the performance of all government agencies, including its non-departmental public bodies".

The watchdog made a number of other comments on the 2008/09 data, including that:

* There has been a "remarkable turnaround" in reducing carbon from administrative road vehicles since 2007/08 - so remarkable that the SDC has questioned the figures. "The results would be difficult to achieve even if the departments had replaced the entire vehicle fleet over the year with the most low-carbon commercially available hybrid vehicles," a spokeswoman said. The watchdog has asked for further information about how the figures have been achieved.

* The targets regime has been "undermined" by the decision of the Treasury and the Department for Culture, Media and Sport to drop the Royal Mint and the Royal Parks respectively from their figures for waste and water because they bring down their department's overall performance score. The SDC also criticises the departments for taking the decision without consulting the watchdog.

* Departments would struggle to successfully take part in the high-profile 10:10 campaign. The Department for Energy and Climate Change has signed up to the pledge, which commits individuals and organisations to reducing their carbon emissions by 10 per cent in 2010, but the SDC has calculated that government "would require a major step change in current performance" if it was to manage such a feat.

* Departments have been urged to look at carbon emissions from other travel - including staff commuting and visitor travel - and called on the Centre for Expertise in Sustainable Procurement (CESP - part of OGC) and departments to settle the ongoing discussion about who should be appointed policy lead on government travel.