The United States is tightening sanctions on Iran to pressure Tehran government to limit its nuclear program and placing similar restrictions on institutions that Washington says are stifling political dissent and censoring speech.

Among the expanded measures announced Monday by the Treasury Department is a move to deny Iran access to revenue garnered from its oil exports. Many countries think Tehran is working to develop nuclear weapons. Iran has said repeatedly that its nuclear program is meant for peaceful purposes.

Under the oil sanctions, Iran would only be able to use revenue from its oil sales in a country that purchased its crude, significantly limiting its access to the money.

The financial sanctions apply to Iran's state-run media, the Islamic Republic of Iran Broadcasting, as well as its director.