Herve Falciani, former IT worker for HSBC, said UK tax authorities would have known about the stolen list of clients of HSBC's Swiss private bank when it was given to French officials.
BBC News reports that it comes as the BBC learned the UK tax authority is to expand its inquiry.
HMRC will meet the police and the Serious Fraud Office later in the week.
Speaking to BBC Radio 4's Today programme, Falciani said French authorities had got in touch with HM Revenue & Customs and passed on information in 2010.
He said the UK government should have known the bank itself was doing wrong in 2010.
'By that time I (had) already declared and explained the problems that were happening,' he said.
'It was made public at that time and of course I already at that time explained the major, huge issues we were foreseeing inside HSBC,' he added.
Hit the link below to access the complete BBC News article: