The Tory trade minister who was chairman of HSBC at the time the bank was allegedly facilitating money laundering for drug king pins, rogue states and terrorists has been accused of dodging questions over what he knew and when.
Lord Green, who stepped down from the top job at the British banking giant in 2010 after being appointed to government by David Cameron, has so far not spoken publicly about the scandal.
Baroness Royall, Labour's leader in the Lords, has said Lord Green should come to parliament to explain his involvement, if any, in the practices uncovered by a US Senate committee.
"Lord Green has spoken in the House a total of just five times," she said in a letter to the Tory leader in the Lords, Lord Strathclyde.
"Previous trade ministers have managed to combine their national and international ministerial duties with their parliamentary responsibilities to a much greater degree," she said.
However Lord Strathclyde said ministers were only required to appear before parliament to explain their actions in office.
"It would therefore not be appropriate for him to make a ministerial statement to the house in relation to matters pertaining to his career prior to becoming a minister," he said.
According to the Guardian Lord Green was last spotted by one Labour party official sitting outside Lord Strathclyde's office "perched on a wooden bench like a naughty school boy".
On Tuesday HSBC apologised after a US Senate investigation accused it of, among other suspect activities, providing services to some lenders in Saudi Arabia and Bangladesh believed to have helped fund al Qaeda and other terrorist groups.
Senator Carl Levin, the chairman of the subcommittee investigating the bank, said the culture of HSBC's non-UK subsidiaries had been "pervasively polluted for a long time" and said senior executives in London "knew what was going on but allowed the deceptive conduct to continue".
Seizing on the scandal, the Labour Party has twice asked that the Tory peer answer questions about it in the House of Lords - requests that have been rebuffed.
Yesterday Ed Miliband said Lord Green had "questions to answer" and that what happened at HSBC was "frankly shocking".
Lord Green joined HSBC in 1982 and rose through the ranks before becoming chief executive in June 2003 and was appointed chairman in 2006.
In 2005 he was made aware of the bank’s alleged ties with “rogue” regimes in the Middle East. And the US Senate investigation has released internal emails showing how in the same year Lord Green was warned by an internal whistleblower in the bank’s Mexico subsidiary that compliance staff had “fabricated records”.
He was also told in 2008, two years after being appointed executive chairman, that the Mexican authorities had uncovered evidence of money laundering that “may imply criminal responsibility of HSBC”.