Culture Secretary Maria Miller has convinced BT to let local authorities reveal details of their plans for the rollout of superfast rural broadband, with the hope that the information will allow other internet service providers to fill in the gaps.

A Public Accounts Committee recently criticised BT for a lack of transparency over the deals being struck with councils, where it is now the only supplier that is able to win contracts on the national superfast broadband framework, and benefit from government funding, after all other ISPs pulled out.

It was also thought that BT was reluctant to release the details of where it will be connecting fibre because it was commercially sensitive.

However, Miller has now written to local authorities urging them to release the plans they have developed with BT as quickly as possible, so that other ISPs and local community providers can work to fill in the gaps.

"We now have 29 signed contracts across the country, representing over 85 per cent of the budget for the rural broadband projects. Rollout is now progressing rapidly, with over 70,000 premises passed to date," said Miller in the letter to local authorities.

"However, as you are probably aware, concerns have been raised about whether information on the areas which will, or will not, be covered by the current projects can be made available. This information will help other broadband providers and community groups determine whether it is worth their while to develop local broadband projects to fill in gaps in coverage.

She added: "It will also help clarify the position of those community broadband projects whose schemes are already planned in some detail. I am keen to see this information made available.

"BT has confirmed to me that it is willing for information on the outline plan for the subsidised footprint to be published, and is happy to support local governments to decide on the right way to do this."

The Culture Secretary also said that she realises that details of coverage are likely to change as design processes are carried out and that the final coverage from projects will not be exactly the same as what is estimate at the point contracts are agreed - many premises will be in the 'to be confirmed' category.

However, Miller still believes that it is worthwhile to make the information public.

She said: "Provided these limitations are made clear, my strong preference is for this information to be made available. I would strongly encourage those of you who have already signed contracts to arrange for the proposed coverage from your project to be published as soon as possible, and for those of you yet to sign contracts to incorporate it into your initial mobilisation activities."

BT said that it is happy to work with councils.

"We are happy to work with local councils who wish to publish the details of their respective BDUK deployment plans. Local councils will decide if and when to publish the outline plans on their website," said a BT spokesperson.