Top tax advisers at Ernst & Young, auditors to Google, Amazon and Facebook, have held a high-level lobbying meeting at Number 10, urging the prime minister not to support calls for financial transparency measures which have been proposed by tax fairness campaigners.

E&Y's UK head of tax John Dixon said he and the firm's global head of tax policy Chris Sanger had taken their lobbying message to Downing Street because "it is not an issue that is going to go away and it is receiving a huge amount of interest at the highest level of our society".

Tax Justice Network (TJN), Global Witness, Save the Children, Cafod and the ActionAid are among the many charities and campaign groups urging governments and the G20 to impose tough rules on multinationals forcing them to report separately on their financial activity for each country in which they operate.

Tax fairness campaigners believe this will help expose aggressive attempts by multinationals to use intra-group transactions as a means to shift profits to low-tax jurisdictions.

So-called country-by-country reporting has already been imposed on mining and oil extraction groups by the US and is shortly to be extended to banks by the EU. "The floodgates are, however, not yet open," said Dixon in a paper published yesterday.

He suggested multinationals should "seize the initiative" and called on them to consider measures to "appease the fair tax lobby" if they want to head off mounting calls for tougher rules to stop them shifting profits to low-tax jurisdictions.

David Cameron, who will host the G8 next month at Lough Erne in Northern Ireland, has made tax transparency a major plank of the summit. Earlier this year he signalled that developing world countries should be able to access information needed "to tackle abuses in the system, so that governments can collect taxes due to them".

Dixon warned pressure to reform the tax treatment of global businesses had reached a "tipping point", adding: "If there is not a step change in the level of voluntary tax transparency reporting, there is a possibility mandatory changes will follow."

E&Y calls for voluntary tax reform were met with some scepticism by long-standing tax campaigners. "It has to be an exercise in wishful thinking to suggest companies can reform without international standards being imposed upon them," said John Christensen, director of Tax Justice Network (TJN). "It [the E&Y report] sounds a bit like: 'God make me good, but not quite yet'."

Last weekend, E&Y chairman Steve Varley told a Sunday newspaper that measures to increase Britain's tax competitiveness were beginning to attract a wave of international companies relocating to the UK. "I know of more than 40 multinational companies that have been looking to undertake global and regional headquarter relocations into Britain," Varley said.

E&Y's calls for voluntary tax disclosures were echoed yesterday by CBI which also called for greater transparency in a "statement of tax principles" that it said were needed to restore the public's trust in corporate Britain. John Cridland, boss of the business lobby group, said the business community was aware that it needed to explain more fully its financial contribution to society.

"We are encouraging firms to introduce narrative reporting, preferably on a sheet of A4 in the annual report, that tells the story in an accessible way about how much tax has been paid and why," he said.

The CBI is concerned that Downing Street will seek to deflect growing criticism of corporate tax avoiders with proposals that require companies to produce country-by-country details of their tax payments.

In January, Dixon admitted to MPs that the OECD rulebook for taxing multinationals "needs to be addressed" in the wake of the emergence of digital businesses. However, the E&Y tax boss has now set out his firm opposition to transparency measures advocated by campaign groups. Dixon said E&Y had carried out a survey of UK firms and found that 70% of tax professionals were opposed to so-called country-by-country reporting.

"I think you have got to come to the conclusion this [calls for tougher policing of multinationals' tax affairs] is not going to go away," said Dixon. "We are actively advising companies that they need to address the issue... They need to think about what type of transparency they should adopt, and how they should adopt it and where they should adopt it."

His remarks come a week after Margaret Hodge, chair of parliament's public accounts committee, suggested Dixon — who has already faced a grilling by MPs in January — might shortly be recalled to give further evidence over the tax affairs of Google along an executive from the search group. No formal request has yet been sent to him.

E&Y has global tax revenues of $6bn and employs about 29,000 experts in offices around the world offering tax advice to clients including multinational groups with controversial tax arrangements such as Amazon, Google, Facebook and Hewlett Packard. In the UK alone, E&Y has 2,081 tax experts generating revenues of £431m, or just over a quarter of total UK turnover.