The Swiss bank said it set up the "special placement vehicles" in 2001 and 2002 at the request of BES, which was fully responsible for selling them.
But it denied reports it had played any role in selling or advising in the sale of the securities, which were issued between 2001 and 2008, and then again in 2012 and 2014.
The Wall Street Journal reported customers bought the SPVs without knowledge that they contained debt from various vehicles within the troubled Espirito Santo group.
The paper was sold as a tool to keep afloat the vast family-run business empire, which has since collapsed amid accusations of vast accounting fraud, the financial daily said.
"At no point did Credit Suisse distribute, sell or advise BES clients and their subsidiaries, whether retail or institutional clients, nor any third party, concerning these SPVs or stock issues by the SPVs," the bank said in a statement.
"Credit Suisse is not exposed to any market risk or credit related to these instruments. In fact, Credit Suisse does not know which of the products was distributed by BES or its branches and subsidiaries," it added.
BES, once one of Portugal's largest lenders, was rescued by the government after it reported a record loss and several of its parent companies filed for bankruptcy.
Lisbon initially pledged €4.4 billion ($5.9 billion) in aid as part of a €4.9-billion rescue package for BES, in a bid to stop its collapse plunging the fragile economy into further crisis.
It subsequently cut the bailout to €3.9 billion thanks to contributions from the financial sector.
Fall-out from the BES scandal has spread beyond Portugal's borders, hitting market confidence in the eurozone economy and sparking rumours that other companies have been involved.
Credit Suisse said it had crafted the Top Renda, EuroAforro Investments and Poupanca Plus Investments SPVs for BES, but not a fourth vehicle, EG Premium, mentioned by The Wall Street Journal.
The newspaper has also claimed that the SPVs were at least partially controlled by a Swiss-based company, Eurofin, which has denied the allegation vigorously.
Eurofin was founded in 1999 by private shareholders. From 2004-2009, the Espirito Santo group owned a 20-percent stake in the company.