U.S. President Barack Obama has ordered stricter sanctions on Iran's government and central bank, citing "deceptive practices" by Iranian banks to conceal transactions.
In an executive order released Monday, the president said other factors for imposing the new restrictions include deficiencies in Iran's anti-money laundering regime, and the "continuing and unacceptable risk" that Iran's activities pose to the international financial system.
The order freezes assets in U.S. control.
The United States and European Union have tightened economic sanctions on the Iranian central bank and oil industry in recent weeks to pressure Iran to stop uranium enrichment -- a process that has military and civilian applications.
Iran recently said it started enriching uranium at its underground Fordo complex, which has the capacity to speed up the production of weapons-grade material.
Israel is reported to be increasingly anxious about Iran's suspected nuclear weapons program and at least one U.S. official is reported to be warning that an Israeli attack is not far off.
Iranian officials deny any intention to build nuclear weapons, and Supreme Leader Ali Khamenei warned last week that Iran will retaliate in full force if its nuclear facilities are attacked.
Western reports say Iranians are reeling under the continuing effects of sanctions.
Faced with a dropping currency, Iranian officials are struggling to stabilize the rial, which has fallen recently on announcements of U.S. and European sanctions against Iran?s banking capability and oil exports.
Some information for this report was provided by AP and Reuters.