US blacklists senior Palestinian Hamas official
Fathi Hammad, who has in the past served as Hamas's interior minister, was named over "coordinating extremists cells."
His party, which runs the blockaded Gaza Strip, is already proscribed by the US as a "foreign terrorist organisation."
"As a senior Hamas official, Hammad has engaged in terrorist activity for Hamas," the Department of State said in a statement.
"Today's action notifies the US public and the international community that Hammad is actively engaged in terrorism," the statement said.
Under the new designation, US citizens and businesses are banned from dealing with Hammad. Any assets he holds in the US will also be frozen.
The statement also said Hammad founded Al-Aqsa TV, "with programmes designed to recruit children to become Hamas armed fighters and suicide bombers upon reaching adulthood".
Hamas has also been designated as a "terrorist organisation" by the EU and Israel, who hold it responsible for rocket attacks launched from the Gaza Strip.
But to its supporters, the group is seen as a legitimate resistance movement, winning a landslide victory in the Palestinian Legislative Council [PLC] elections in 2006.