The Obama administration is hitting three top Syrian officials, Syria's intelligence agency and Iran's Revolutionary Guard with sanctions because of the brutal crackdown on pro-reform demonstrators in Syria.

The penalties to be announced Friday will freeze any assets that the officials, Syria's General Intelligence Directorate and the Iranian Revolutionary Guard Corps may have in U.S. jurisdictions and also bar Americans from doing business with them. Two senior U.S. officials said President Barack Obama authorized the sanctions to punish repression and human rights abuses committed by Syrian authorities seeking to quell five weeks of protests. More than 450 people have been reported killed.

The officials would not name the individuals to be penalized pending formal release of Obama's executive order and an annex that will identify them. However, they said Syrian President Bashar Assad is not among those included in the annex. Assad could be named later if the crackdown continues, they said. The officials spoke on condition of anonymity before the announcement.

While the sanctions are likely to have limited direct impact because none of the targets is believed to have any significant assets in U.S. banks, the officials said the move was aimed at sending a clear message to the Syrian people that those responsible for the crackdown are going to face consequences and no one in the Syrian leadership will be immune.

Syria already is under U.S. sanctions as it is designated a "state sponsor of terrorism" by the State Department. The new sanctions extend the penalties to individuals.

Iran and its Revolutionary Guard Corps also are under similar U.S. sanctions. The officials said the new designation for the Revolutionary Guard would add another layer of penalties and make clear that Washington believes it is providing material support to help Syrian authorities with the crackdown.