The government will close around three-quarters of its websites and halve costs on the remainder, in a bid to save £100 million.

Some 600 sites will either be entirely eliminated or will move data to the existing portal, leaving around 200 websites operational. A review informing the next steps will report back by September, and will advise how the remaining sites can shift onto common infrastructures.

The move builds on efforts by the previous government, which since 2008 has closed 1,001 sites and said new websites could not be established without approval.

But three months later it backtracked and said it would not ban new local government websites, after admitting the original decision had been taken without consulting councils.

The announcement comes in the wake of an official report that many websites have low usage and high costs. The worst examples were, which has running costs equivalent to £11.78 per visit, and, which costs £2.15 per visit. Last year, the government spent £126 million setting up, maintaining and staffing 46 of the more expensive sites.

There are also issues over efficiency, with 40 per cent of surveyed visitors to the Department of Work and Pensions site complaining they found none of the information they were looking for.

Francis Maude, the Cabinet Office minister who ordered the change, said all sites "will be subject to a review looking at cost, usage and whether they could share resources better", with the review suggesting which sites should be closed. Any new sites will have to obtain central approval.

Sharing infrastructure, as well as data, will be key steps for the remaining websites. The government's 'digital champion', Martha Lane-Fox, will advise on how to share resources and use more open source software, as well as on how put more services online.

Many sites have been competing against each other, with the Department for Energy and Climate Change and the Energy Saving Trust bidding against each other for Google search terms.

The sites were also sending conflicting messages, with from the Potato Marketing Board telling the opposite story from the Department of Health's Change4Life campaign. "The days of vanity sites are over," Maude said, adding that the government web needed to be brought back "under control".