The Canadian bank reported to be interested in acquiring a stake in AIB, Canadian Imperial Bank of Commerce, had to settle charges that it helped Enron mislead investors in a period of several years. The bank has also posted the largest level of sub-prime losses of any Canadian bank.

Three executives from the bank, who have no connection to the Enron charges, recently visited the minister for finance, Brian Lenihan, for a meeting also attended by Lenihan's head of banking Kevin Cardiff.

It is understood the bank has proposed a co-investment in AIB with the government, post-Nama. However, AIB executives remain hopeful they can avoid a takeover next year when Nama completes its work.

Canadian Imperial has not been named by AIB, but the "third party" is believed to be this bank. Reports late last week said the interested party was Royal Bank of Canada, but this is not thought likely.

Back in 2003, Canadian Imperial Bank of Commerce had to pay $80m to settle charges it helped Enron's accounting fraud. At the time the Securities & Exchange Commission (SEC) said it had charged Canadian Imperial and some of its executives with "having helped Enron to mislead its investors through a series of complex structured finance transactions over a period of several years".

"Today's action demonstrates that neither financial institutions nor their executives can hide behind the technical complexities of structured transactions," the SEC enforcement section said at the time.

According to Bloomberg data the bank has posted C$10.7bn in pre-tax debt writedowns since the collapse of the US subprime mortgage market in 2007. In 2005, it had a quarterly loss of C$1.91bn on costs relating to Enron.