The Obama administration on Thursday accused Iran of assisting Syria’s government in its brutal crackdown on demonstrators, listing names of Iranian security officials that the White House says helped train and arm Syrian police to attack peaceful protesters.

Sanctions unveiled by the Treasury Department identified Iran’s national police force and a pair of senior Iranian officials, one of whom allegedly traveled to Damascus in April to offer expertise on dealing with the country’s protest movement, White House documents showed. While the United States has previously accused Iran of backing the crackdown, Thursday’s statement was the first to provide specific names and dates.

“We are exposing further Iran’s provision of its military and security forces to support the Syrian government’s ongoing violence and repression of the Syrian people,” said David S. Cohen, the department’s acting undersecretary for terrorism and financial intelligence. Cohen said the moves build on weeks of previous sanctions intended to “end the use of wanton violence” by forces loyal to Syrian President Bashar al-Assad.

The Iranian officials hit with sanctions included Ismail Ahmadi-Moghaddam, the chief of Iran’s Law Enforcement Forces (LEF), and his deputy, Ahmad-Reza Radan. A Treasury statement accused Radan of traveling to Syria in April to provide “expert aid in the Syrian government’s crackdown on the Syrian people.”

The law-enforcement force also had dispatched representatives to Syria’s secret police, the Syrian General Intelligence Directorate, to train its agents on dealing with the country’s worst political unrest in decades, Treasury Department officials said.

The new sanctions, which also target a Syrian security official, freeze any U.S. assets owned by the individuals and prohibit Americans from conducting business with them.

Radan and the LEF previously had been accused of orchestrating the Iranian government’s crackdown on dissidents in Tehran following Iran’s disputed national elections in June 2009.

Separately, Obama administration officials said Rep. Dennis J. Kucinich (D-Ohio) had embarked on a fact-finding trip to Syria and Lebanon. Kucinich was traveling to the region “at his own instance and at the request of his constituents,” the State Department said.