Jerusalem ? The U.S. government has barred Americans from doing most business with the new Hamas-led Palestinian government, officials said Friday, stepping up U.S. financial pressure on the Islamic militant group.

In a memo obtained by The Associated Press, the U.S. Treasury Department said “transactions with the Palestinian Authority by U.S. persons are prohibited, unless licensed.” It said the decision was based on “existing terrorism sanctions.”

The United States and European Union have branded Hamas, which has killed hundreds of Israelis in suicide attacks, a terrorist group.

The U.S. and the EU have cut off hundreds of millions of dollars in aid to the Palestinian Authority following Hamas’ victory in Palestinian legislative elections, demanding the group renounce violence and recognize Israel.