WASHINGTON (AP) — The Obama administration wants US banks to enhance monitoring of exchange houses in the Middle East and elsewhere for Iranian attempts to evade economic sanctions.

The Treasury Department says Iran is gaining access to the American financial system through the loophole of exchange houses and trading companies in countries not subject to US sanctions.

The department says it has identified transactions that conceal Iranian companies and account holders, including people designated under US sanctions law.

It said Thursday that US banks do not need to close accounts held by exchange houses. But they should be diligent about where funds come from.

Washington is stepping up pressure on Iran over its nuclear program. The US fears Iran may be trying to develop nuclear weapons; Iran says its program is for energy production.

Copyright 2013 The Associated Press.