The United States on Thursday put more than 50 Iranian entities under sanctions in its latest efforts to stifle the Islamic republic's nuclear and ballistic missile programs.

According to the Department of Treasury, by publicly identifying a group of Iranian front companies and banks, the additional sanctions targeted Iran's "nuclear and ballistic missile proliferation networks" and intended as well to prevent the evasion of sanctions.

"These actions are part of the United States government's dual- track approach of increasing pressure to convince Iran to engage seriously and address the international community's concerns about its nuclear program," the Treasury said in a statement.

In what the agency called continuous efforts to target Iran's nuclear and missile proliferation activities, 11 Iranian entities and four individuals were blacklisted, many of whom are part of a network of proliferators led by Iran's Ministry of Defense for Armed Forces Logistics and its subsidiary, Aerospace Industries Organization.

Some others are related to Iran's national maritime carrier, Islamic Republic of Iran Shipping Lines, and Iran's Islamic Revolutionary Guard Corps, both of which have been targeted for sanctions many times by Washington and its allies, the Treasury said.

In a move to prevent what it called the circumvention of international sanctions, the Treasury exposed many front companies and ships in addition to 20 financial institutions, all owned by the Iranian government.

Among them are Petro Suisse Intertrade Company SA, Hong Kong Intertrade Company, Noor Energy (Malaysia) Ltd. and Petro Energy Intertrade Company, four front companies for the Naftiran Intertrade Company or the National Iranian Oil Company.

The National Iranian Tanker Company, along with its 58 vessels and 27 affiliated entities, was targeted as well.

"These identifications highlight Iran's attempts to evade sanctions through the use of front companies, as well as its attempts to conceal its tanker fleet by repainting, reflagging, or disabling GPS devices," the Treasury said.

"Iran today is under intense, multilateral sanctions pressure, and we will continue to ratchet up the pressure so long as Iran refuses to address the international community's well-founded concerns about its nuclear program," said David Cohen, under secretary of Treasury for terrorism and financial intelligence.

"Today's actions are our next step on that path, taking direct aim at disrupting Iran's nuclear and ballistic missile programs as well as its deceptive efforts to use front companies to sell and move its oil," he added.

The UN Security Council imposed four rounds of sanctions on Iran between 2006 and 2010 over its refusal to halt its nuclear enrichment program, which Western countries suspect could be used to develop nuclear weapons.

Despite Iran's insistence that its nuclear program is for civilian use only, the United States and European Union have imposed extra sanctions of their own and continued their expansion over the years to cover lately Iran's oil exports, the lifeline for the country's economy.

Iran had held three rounds of talks with the U.S., Britain, France, Russia, China and Germany over its uranium enrichment program since mid-April plus one at the expert level.