Credit Suisse continues to help ultra-wealthy Americans evade taxes and had concealed more than $700 million from tax authorities in violation of a 2014 plea agreement, the U.S. Senate Finance Committee said Wednesday.

After concluding a two-year investigation into Credit Suisse, the committee said it had uncovered "major violations" of the 2014 agreement between the Swiss lender and the U.S. Department of Justice for enabling tax evasion.

These violations included failing to disclose nearly $100 million in secret offshore accounts belonging to a single family of American taxpayers, which it said represented an "ongoing and potentially criminal conspiracy."

In an emailed statement, Credit Suisse said it did not tolerate tax evasion and had been cooperating with U.S. authorities.

"Credit Suisse’s new leadership team has cooperated with the Committee’s inquiry and has supported the work of Senator Wyden, including in respect of suggested policy solutions to help strengthen the financial industry’s ability to detect undisclosed U.S. persons," the bank said, referring to Senate Finance Committee Chairman Ron Wyden.

In a statement Senator Wyden said: "At the center of this investigation are greedy Swiss bankers and catnapping government regulators, and the result appears to be a massive, ongoing conspiracy to help ultra-wealthy U.S. citizens to evade taxes and rip off their fellow Americans."

Representatives for the U.S. Department of Justice did not immediately respond to a request for comment.