Reports about rampant use of tax havens are a reminder that "tax avoidance is a big global problem," US President Barack Obama says, in his first comments on revelations contained in the so-called Panama Papers.
He says combating illicit tax havens has been an important top of international meetings.
"There's always going to be some illicit movement of funds around the world, but we shouldn't make it easy," the US president says. "We shouldn't make it legal to engage in transactions just to avoid taxes."
Obama also defends the effectiveness of US sanctions, saying: "We know the sanctions regime is strong, because Iran wouldn't have, for example, cut a deal to end their nuclear programme in the absence of strong sanctions enforcement."