A committee of MPs have described the UK's £130 million tax settlement with Google as "disproportionately small".
The Public Accounts Committee (PAC) chair, Meg Hillier MP, said public anger over the deal was "palpable".
Google has insisted that the settlement was "fair" and the Chancellor George Osborne hailed it as a "great victory" for the UK's tax efforts. But critics claim that it amounts to Google paying a corporation tax rate of just 3% over the past 10 years.
The MPs said it was impossible to judge whether or not the deal was fair for taxpayers, given the lack of transparency surrounding the details of the settlement.
The PAC said it was concerned that HMRC "appears to have settled for less" corporation tax than other countries - just days after the UK's deal was announced, Italy's tax authority secured a larger settlement.
In its recommendations, the MPs said HMRC needs "to lead the way in pressing for changes to international tax rules to prevent aggressive avoidance by multinational companies."