A US Treasury official met on Monday in Lebanon with president Michel Aoun and prime minister Saad Hariri after Washington announced a probe into Hizbollah “narcoterrorism”.
On January 11, the US Justice Department said it was creating a task force targeting the Iran-backed Lebanese group, Hizbollah, which America considers a terrorist organisation.
Hizbollah is represented in both the government and parliament and has since 2011 played a key role in the war in Syria, where it is fighting alongside forces loyal to Syrian president Bashar Al Assad against the rebels.
"Lebanon is an active participant in global efforts to fight the financing of terrorism and money laundering," Mr Aoun said in a statement.
"Lebanese security services are vigilant in the pursuit of terror cells and the fight against drug trafficking.”
Editorial: A threat to Hizbollah's illegal drug trade
In 2015, America adopted a law for sanctions against banks that knowingly finance Hizbollah.
Hizbollah chief Hassan Nasrallah on Friday denied that his militia was involved in drug trafficking to finance itself.
"These are unfair accusations that are not based on any fact, that are not true," he said.