The inclusion of a UK postcode database as part of the Royal Mail flotation has been criticised by the Public Administration Committee (PAC), which has branded the exercise as a "mistake".
The committee, which is a group of influential MPs, said that the Postcode Address File (PAF) was included in the sale of Royal Mail to "boost the share price at flotation" - an accusation denied by the government.
PAC said that its inclusion took "an immediate but narrow view of the value of such datasets".
It added that the database should have been retained as a public data set and a national asset.
Bernard Jenkin, chair of PAC, called the sale "a mistake", and went on to state that access to public-sector data must never be sold or given away again.
He explained that the information is very expensive to collect and collate into usable form, but that it has a huge potential value to the economy and society as a whole "if it is kept as an open, public good".
Jenkin commended the UK government for being an early mover on government open data, but said that if it didn't take the opportunities offered, then businesses with growth potential may be deterred by fees for data, and by legal and administrative barriers.
He said that there should be a presumption of openness and a willingness to publish early even if the data was imperfect.
"There is much to be gained from open data, but the government's direction of travel is not clear. Open data needs to be treated as a major government programme in its own right, with the active leadership and management which are the only way to realise the substantial benefits that are within our grasp," he explained.
A spokesman for the Department for Business, Innovation and Skills told the BBC that the PAF was included in the sale of Royal Mail because "it is an integral part of its operations, not to boost the price".
Royal Mail said it was looking to make PAF more widely accessible "at a fair price".