* Damascus, Tehran try to get around sanctions
* Foreigners who help can be barred from U.S. banking
* U.S. says sanctions working, intend to keep pressure on (Recasts lead, adds comments from senior Treasury official)
WASHINGTON, May 1 (Reuters) - The Obama administration announced on Tuesday that it will target foreigners who help Iran and Syria evade U.S. sanctions and bar them from access to the U.S. banking system.
The latest tightening of existing sanctions, announced in the form of a White House executive order giving the Treasury Department expanded authority, aims to stop foreign firms from completing banned transactions with Syria or Iran.
“Whoever tries to evade our sanctions does so at the expense of the people of Syria and Iran and they will be held accountable,” said David Cohen, undersecretary for terrorism and financial intelligence.
At a later briefing, a senior Treasury official who spoke on condition of anonymity said sanctions intended to halt Iran’s nuclear program and stop Syrian government aggression against its own citizens, were working but were leading to new efforts by Tehran and Damascus to circumvent them.
“Both countries are seeking to use non-bank financial institutions - money service businesses, currency exchanges, trading companies and other entities to facilitate payments and transmit funds,” the official said.
No specific foreigner or foreign-owned entity was named on Tuesday as a violator.
The Treasury official said the department would use the new authority to “continue the steady, methodical and unflinching application of our sanctions programs against Iran and Syria.”
Pressed to explain how the new powers differ from existing sanctions rules, the official said Treasury will have “a more nimble and agile ability to go after persons who may be evading our sanctions.” The department would be able to target foreigners who it now has problems prosecuting because they are not based in the United States.
“It is only focused on foreign persons and entities,” the official said, adding U.S. citizens would be prohibited from any dealing with such foreign entities.
The official declined to respond at length when asked whether foreign governments or individuals might run afoul of the expanded Treasury powers if they engaged in barter, such as trading goods for oil with Iran.
“That’s a complicated question and one that I‘m not going to try to venture and answer right here,” the Treasury official said, adding that if a transaction was structured to be deceptive and to evade sanctions then it could cause problems for the foreign entity.
The Obama administration has been steadily tightening restrictions against the Syrian and Iranian governments, working with governments around the world to pressure the regimes.
Obama signed a sanctions law in December that targets Tehran’s ability to sell crude oil.
Last week, new U.S. sanctions were imposed on those who help Syria and Iran track dissidents through cell phones and computers.
Although a ceasefire is supposedly in place in Syria, violence continues and on Tuesday a rights group reported 10 civilians dead and 12 soldiers killed in a firefight with rebel forces.
The United Nations says more than 9,000 Syrians have been killed since an uprising against the government of President Bashar al-Assad began in March 2011. (Reporting by Jason Lange and Glenn Somerville; Editing by Doina Chiacu and Bill Trott)