The UK's City of London watchdog was not informed of the HSBC tax allegations before they were released in the media this week, according to chief executive Martin Wheatley.
The head of the Financial Conduct Authority has told UK legislators that he was "not aware" of the FCA being briefed on the claims made about the Swiss private banking arm of HSBC.
The UK's HM Revenue and Customs (HMRC) received documents relating HSBC's possible role in helping its clients avoid tax in 2010 but it appears that the body did not inform the financial watchdog over the issues.
A spokesman told the BBC that HMRC was unable to pass on the information because of a deal with France: "We received the data under an international treaty agreement with France which had tight restrictions. We couldn't move it outside the department."
Wheatley reiterated that there was not a problem with the way that HMRC had communicated with the FCA over the HSBC leaks.
"I don't know if they have such an obligation," Wheatley told MPs, adding that the way HMRC acted "doesn't stop us doing our job".
The FCA was carrying out a number of investigations into the UK's banking sector and pursuing its reform campaign, Wheatley added.
The watchdog has "a number of ongoing investigations which will raise further questions about the banks", he said.
"We do have a deep programme of reform in a number of banks regarding anti-money laundering and HSBC is one of the banks we're working closely with," he added.
A number of relevant authorities across the globe, including the US, Argentina, France and Switzerland, are mulling whether to investigate HSBC's actions in assisting its clients avoid paying tax.