A committee of MPs has urged HM Revenue and Customs (HMRC) to "fully investigate" Google after more information obtained by whistleblowers has undermined the company's tax policies.
The main issue stems from advertising sales, which Google says takes place in Ireland where taxation is lower, instead of the UK.
However, the Public Accounts Committee has been told by former Google employees that UK-based staff are also engaged in selling.
The firm made $18 billion in revenue from the UK between 2006 and 2011, but paid just $16 million in UK corporate taxes in that time.
According to the committee, it was "extraordinary" that HMRC did not challenge Google over "the complete mismatch between the company's supposed structure and the substance of its activities".
HMRC head of business tax Jim Harra commented: "Since 2010 we have collected over £23 billion ($36 billion) in extra tax through challenging large businesses' tax arrangements."
Google said it complied with all the tax rules in the UK.
By Asim Shah