The figures show that ministers met corporate representatives on 1,537 occasions in the first 10 months of the coalition. This excludes several hundred round-table meetings where numerous companies were present.

Trade bodies, thinktanks and other interest groups had 1,409 meetings. By contrast, charities were met on just 833 occasions, and union representatives just 130 times, less than a tenth as often as their corporate counterparts.

Tamasin Cave, of the lobbying transparency group Spinwatch, said the records of ministerial meetings showed the wide extent of corporate networks of influence, but she also warned they may merely scratch the surface.

"The findings show a massive disparity in ministerial access for different types of groups – corporate interests clearly have privileged access. But these are just the meetings we know about: Conservative ministers in particular are meeting outside interests in a private capacity.

"This just can't be done when ministers are meeting those who have commercial interests. In this context, private simply means secret."

Cave added that her organisation was engaged in a freedom of information battle with Cabinet Office minister Mark Harper, who is overseeing the coalition's plans to introduce a lobbying register. Harper, she alleges, is resisting an FoI request asking for details of his meetings with lobbyists to discuss lobbying transparency.