The US Treasury Department on Thursday sanctioned a Turkey-based company and three foreign nationals for moving money for Hamas through an underground banking network.

El-Kahira for General Trading, registered in İstanbul, transferred hundreds of thousands of dollars for Hamas, according to the US Treasury Department’s Office of Foreign Assets Control (OFAC).

OFAC also sanctioned the company’s Palestinian owner, Khaldun Khamis Zakaria Alden, and its Iraqi shareholders, Zaid Issam Ahmed Al-Jebouri and Abdulla Issam Ahmad Al-Jebouri.

The sanctions block any property and interests in property the four targets have in the United States or under the control of US persons, with US citizens and companies barred from conducting transactions involving them. Foreign financial institutions could face secondary sanctions for facilitating transactions on their behalf.

The measures were part of a package that included a UK-based Egyptian Muslim Brotherhood official and Hamas-linked organizations in Gaza and Indonesia. Washington designated Hamas as a foreign terrorist organization in 1997 and has imposed rounds of sanctions on people and charities it accuses of financing the group.