The Obama administration on Thursday added a top businessman to the list of Syrians it is sanctioning for human rights abuses amid a government crackdown on pro-democracy demonstrators.

The Treasury Department said businessman Muhammad Hamsho would face sanctions for his ties to President Bashar al-Assad and his brother Mahir, a military leader.

The Syrian government’s efforts to crush a four-month-old uprising have sparked international condemnation. The U.N. Security Council on Wednesday condemned Syria’s use of violence against protesters, and U.S. lawmakers have been clamoring for tougher sanctions on the Damascus government.

“Muhammad Hamsho earned his fortune through his connections to regime insiders, and during the current unrest, he has cast his lot with Bashar al-Assad, Mahir al-Assad and others responsible for the Syrian government’s violence and intimidation against the Syrian people,” said David S. Cohen, undersecretary for terrorism and financial intelligence. “The sanctions we are applying today to Hamsho and his company are the direct consequence of his actions.”

The Obama administration had already announced sanctions against President Assad and several other members of his inner circle in May. The measures bar Americans from doing business with the targeted Syrians, and freeze their U.S. assets.

So far, sanctions imposed by the United States and the European Union have done little to dissuade the Syrian government from cracking down. It has besieged the opposition stronghold of Hama this week, reportedly killing scores of people in an effort to crush the uprising.

Hamsho, who is also a member of parliament, is chief executive officer of Hamsho International Group, a Syrian holding company that has about 20 subsidiaries or affiliates, according to the Treasury statement. The company was also put on the sanctions list.