Ministers held more than 1,500 meetings with corporate representatives in the first 10 months of the coalition, according to a Guardian analysis which has prompted claims of a "massive disparity" in access.

As the Liberal Democrats indicated that they would use the resignation of Liam Fox to speed up the introduction of a register of lobbyists, the Guardian publishes figures showing the extent of the government's links with business.

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.

William Hague said on Sunday that the regulation of lobbyists would be examined after the cabinet secretary, Sir Gus O'Donnell, publishes his report into Fox's links with Adam Werritty Tuesday. "I think we'll have to take stock of that. I think ministers will have to discuss that, but with the advantage of having seen that report," the foreign secretary told The Andrew Marr Show on BBC1.

It is understood that Downing Street will implement any changes recommended by O'Donnell. But ministers believe the Fox saga is unlikely to highlight any systemic problems with lobbyists. "There really aren't any members of the cabinet who operate in that way," one government source said of Fox.

Nick Clegg and other Lib Dem ministers share this analysis. But they are planning to use Fox's resignation to intensify pressure on the Tories to honour their coalition agreement commitment, which states: "We will regulate lobbying through introducing a statutory register of lobbyists and ensuring greater transparency."

Ministerial meetings Photograph: Official records

Lib Dem sources said the review into lobbying, which is being run by Harper and the Lib Dem deputy Commons leader, David Heath, had slowed after pressure from the lobbying industry.

One source said: "We are pushing hard on this. It ran into a bit of push-back from the lobbying industry. Nick Clegg and David Heath are trying to push it to give it a bit of momentum. The events of the last week will give it a shove in the right direction."

Lib Dems believe the prime minister has little room for manoeuvre after he described the £2bn lobbying industry as the "next big scandal" in a high-profile speech in February 2010.

The O'Donnell report is expected to make uncomfortable reading for Fox. Jon Moulton, the venture capitalist who made a donation to a company, Pargav, which helped fund Werritty's trips, is understood to have approached O'Donnell to claim that he was "misled" by Fox.

Moulton was reported in the Sunday Times as saying that Fox had personally vouched that any money he gave to Pargav would be used to fund research.

Clegg admitted on Sunday night that the allegations about Fox had damaged the government. The deputy prime minister told Pienaar's Politics on BBC Radio 5 Live: "The reputation of politics and government generally, of course, is harmed when you've got this kind of salami-slice of daily revelations and allegations."

The figures published by the Guardian show that no department has published its record of meetings for any month more recent than March 2011 despite the coalition's pledge to regularly publish details of ministerial meetings. Several, including the Department for Media, Culture and Sport, the Home Office and Department for International Development have not even published the full log of meetings up to that point.

Other declarations could be described as less than transparent: home office minister Lynne Featherstone records a meeting with "various companies", while culture minister Ed Vaizey meets with "major publishers" to discuss "numerous issues".

A spokesman for the Department for Business, Innovation and Skills, which had the most meetings with outside interests, said in response to the Guardian figures that business did not enjoy any additional access to government.

"No organisations or individuals with a genuine interest in talking to us are excluded or discouraged from contacting and engaging with this department," he said. "The government's top priority is to achieve sustainable and balanced growth. This requires frequent contact with businesses, and business organisations, of all sizes. These relationships are essential to our understanding of business concerns and needs, and are even more crucially important in these challenging times."

Separate analysis of declared outside interests of MPs' staff and researchers found that dozens of MPs employ individuals with links to defence consultancies, major businesses, and lobbying groups. The Christian lobby group Care (Christian Action Research and Education), which helped to support Nadine Dorries's proposed abortion amendment last month, has connections with researchers working for six MPs, in several instances offering bursaries to fund researchers' time in Westminster.

PricewaterhouseCoopers and KPMG are both listed as having links with parliamentary staff, as are numerous smaller consultancies such as Clearwater and Titon. Outside-funded overseas travel was also declared, including a visit to the Paris Air show for the Tory MP Jack Lopresti and his researcher, paid for by the global missile company MBDA.

In total, more than 311 of the 1,650 parliamentary passholders declared some form of outside interest, though these included employment with political parties.

John Mann, Labour MP for Bassetlaw who campaigns against the ease with which lobbyists gain parliamentary passes, said: "A parliamentary pass is worth its weight in gold to a lobbyist.

"Once they have one in their hands, they can wander around the Palace of Westminster, use it to access politicians, peers and civil servants they want to access and they can do it quietly, quickly and with little trace.

"And what is so important is that they can hold informal meetings with power-brokers that never have to be declared - the public need never know, and their influence remains hidden from the parliamentary authorities, from the public and, in some cases, from the police. It is a scandal."

• See the full, searchable records of meeting and staff interests here