Speaking ahead of a meeting of G8 interior ministers in Rome, Antonio Maria Costa told Reuters that the freeze in interbank lending meant crime gangs were the "only ones left holding large amounts of cash".
In 2005, he said organized crime syndicates held an estimated $322 billion in cash and last year, a raid on a suspected drug trafficker's home in Mexico City recovered $206 million in bank notes - thought to be the largest cash seizure in history.
"We are talking about ... syndicates which have become a threat to security in a number of regions," he stated.
Mr Costa said regulatory reform presented an opportunity to expand anti-money laws beyond financial transactions to cover "vulnerable" sectors such as real estate, gambling and the hotel industry.
UNODC was established in 1997 by the merger of the Centre for International Crime Prevention and the United Nations Drug Control Programme.