U.S. Treasury Secretary Timothy Geithner announced on Wednesday that the U.S. government will extend sanctions on more Iranian individuals and firms due to Tehran's suspected nuclear program.

"Our actions today are designed to deter other governments and foreign financial institutions from dealing with these entities and thereby supporting Iran's illicit activities," Geithner said.

"In the coming weeks we will continue to increase the financial pressure on Iran," he added.

The additional sanctions, imposed by the U.S. government beyond the new UN Security Council resolution on Iran, target Post Bank of Iran, Islamic Revolutionary Guard Corps entities and individuals, five Islamic Republic of Iran Shipping Lines front companies and so on, according to a statement released by the U.S. Treasury Department.

"All transactions involving any of the designees and any U.S. person are prohibited, and any assets the designees may have under U.S. jurisdiction are frozen," the statement said.

Last Wednesday, UN Security Council resolution adopted the fourth round of sanctions against Iran.

The resolution builds on existing UN sanctions imposed since 2006 and expand the breadth and reach of such measures by creating new categories of sanctions.