Former City minister Lord Myners has torn into reforms announced on Monday aimed at preventing another banking crisis.
The Labour peer said the Independent Commission on Banking (ICB) had simply failed to address some of the most critical issues confronting the banking industry.
He also accused the ICB, under Sir John Vickers, of swallowing "hook, line and sinker" lines produced by the bank lobby.
Lord Myners also branded the proposed timetable for implementing the reforms by 2019 as "unnecessarily generous" to bankers.
However despite his strong reservations, he said the reforms were "better than doing nothing" and urged ministers to get on with them.
Tory former chancellor Lord Lawson of Blaby swiftly hit back, accusing the last Labour government of introducing the "most disastrous and dysfunctional system of banking regulation imaginable". However he too warned that the system of ring fencing lenders' retail and investment divisions, proposed by the ICB, could prove inadequate.
Opening a debate on the ICB report, Lord Myners said it "simply fails to address some of the most critical issues currently confronting us in terms of establishing a safer and more economically effective banking system".
He said a "massive lacuna" lay at the heart of the Vickers report. It spent no time at all examining the causes of the collapse of the banking system and learned no lesson from this.
"He appears to have completely overlooked a number of issues in his terms of reference. He says nothing about moral issues, which he was asked to address. He doesn't examine radical solutions. He doesn't look at the case for proposing a new enterprise bank. He is strong in assertion but weak, in many cases, in evidence and lazy, quite frankly, in one important piece of evidence.
"That said, it is better than doing nothing. And on that basis we should get on with it rather than delay implementation, as has been suggested."