The New York Federal Reserve fined Switzerland's

UBS

(UBS) - Get Report

$100 million for violating a U.S. embargo on banking transactions with Cuba, Iran, Yugoslavia and Libya.

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The Fed took the action after discovering employees at UBS tried to conceal that the bank had violated the embargo by trading in U.S. dollars with financial institutions in the those four countries.

The Fed had selected UBS to participate in a program to buy-up old dollar notes and replace them with new bills.

The bank, which said it dismissed several employees over the incident, apologized for its actions.

"UBS recognizes that very serious mistakes were made," UBS Chief Executive Officer Peter Wuffli said in a prepared statement. "We accept the sanctions, take full responsibility, and would like to express our regret."

The Fed's investigation found that UBS employees tried to conceal the trading by falsifying monthly reports submitted to the Fed.