Big companies should be forced to publish their tax returns as part of efforts to clamp down on avoidance and evasion, an independent review commissioned by Labour has recommended.
The first stage of the review of HM Revenue and Customs said related documents and calculations should also be publicly available.
Parliamentary committees should be empowered to examine sensitive tax information, with MPs and peers deciding whether scrutiny of documents and practices should be conducted behind closed doors, it said.
The review by Professor Prem Sikka of the University of Essex also called for the creation of a supervisory board for HMRC to "act as a bulwark against corporate capture and inertia", accountable to parliamentary committees.
That board should also protect tax whistleblowers, the report said.
Shadow chancellor John McDonnell said the study lent weight to Labour's argument that HMRC needs to be more accountable and have more resources to deal with tax avoidance and evasion.
"The public want to urgently see more action on tax avoidance but the Government have made things worse by cutting staff and resources at HMRC. This report lends further support to something we have been arguing for years: that HMRC needs more accountability and resources to deal with tax avoidance and evasion.
"Labour will be looking at the report's recommendations in great detail while we develop our policies in this area, and also discussing how to take the review forward to the next stage.
"It's only under a Labour government that the UK can get a serious grip on the problems of tax avoidance and evasion."
The report also called for HMRC to be given more cash for resources and staffing, to restore a local network of offices, and to be given extra funds for investigations and prosecutions.
Professor Sikka said: "HMRC performs a vital task in collecting taxes, enforcing lax laws and delivering services to taxpayers. Against a background of reductions in resources, it has experienced considerable difficulties in meeting the service expectation of taxpayers and challenging organised tax avoidance. We have investigated the difficulties and made recommendations to strengthen HMRC and its public accountability."