An open government campaigner who has advised the government is to help the Conservative Party, it has been announced.

Tom Steinberg, founder and director of the democracy website MySociety and co-author of the government's Power of Information report, is to advise the Tories on IT policy.

Steinberg, who has also worked as a civil servant in the prime minister's strategy unit between 2001 and 2003, has been a committed supporter of agendas such as Freedom of Information, open source software and open data.

The Conservatives have shown a willingness to commit government to such ideas, with regular calls for departments to use more open source software, and a promise that any spending over £25,000 would be published online.

Following media reports of the announcement, Steinberg wrote on his blog: "I have enjoyed advising this government, and I look forward to advising the next."

His Power of Information report, published in 2007, advised government to interact more closely with established web communities such as mumsnet.

The appointment, which is expected to be formally announced at the Conservative Party conference in Manchester, has been criticised by Labour MP Tom Watson, who was transformational government minister at the Cabinet Office when Steinberg was examining the issue of public sector information for the department.

Watson, writing on his own blog, claimed that the announcement of the appointment at the Tory conference is "incompatible with his [Steinberg's] position as boss of MySociety".

He continued: "They’re a non-partisan organisation who rightly, take a dig at all sides when required. The manner of his appointment will leave an air of mistrust between him and supporters of MySociety who are not Conservatives. That’s a very great shame for him, but more importantly, for MySociety."

Steinberg, who expressed his sadness at being criticised by "someone I’ve had such a good working and informal relationship with", has insisted that MySociety would continue to be "rigorously impartial, just as it was when I was advising ministers like you [Watson] in the current government".