Islamic State militants have looted up to $1 billion from bank vaults in Syria and Iraq and has made at least another half a billion dollars from black market oil sales, senior U.S. Treasury official Adam Szubin said on Thursday.

¡°ISIL has made more than $500 million from black market oil sales,¡± Szubin, acting undersecretary for terrorism and financial intelligence with the U.S. Treasury, said in remarks prepared for delivery.

¡°It has looted between $500 million and $1 billion from bank vaults captured in Iraq and Syria,¡± Szubin said. ¡°And it has extorted many millions more from the populations under its control, often through brutal means.¡±