WASHINGTON - The US Department of the Treasury has said that it has imposed new sanctions on Iran for its ballistic missile programme.

The department made the announcement in a statement issued on Sunday, only a day after sanctions targeting Iran’s nuclear energy programme were lifted.

The statement said five Iranian citizens and a network of companies based in the United Arab Emirates and China were added to a US blacklist.

The network "obfuscated the end user of sensitive goods for missile proliferation by using front companies in third countries to deceive foreign suppliers," the statement said, adding, that the five people had "worked to procure ballistic missile components for Iran."

"Iran's ballistic missile programmw poses a significant threat to regional and global security, and it will continue to be subject to international sanctions,” said Adam Szubin, Acting Under Secretary for Terrorism and Financial Intelligence.

On Oct 11, Iran’s Islamic Revolution Guards Corps (IRGC) successfully test-fired its first guided ballistic missile dubbed Emad.

The US slammed the test, claiming the projectile is capable of carrying a nuclear warhead. It vowed to respond with more sanctions.

But Iranian Defence Minister Brigadier General Hossein Dehqan said the Emad missile was a conventional weapon. The Iranian media have aired footage of an underground missile facility of the IRGC packed with Emad missiles.

On Saturday, US President Barack Obama signed an executive order lifting US economic sanctions on Iran.

Obama’s move came after the International Atomic Energy Agency (IAEA) verified that Iran has implemented its commitments made in the Joint Comprehensive Plan of Action (JCPOA), and announced to remove international economic sanctions against the country.

Iran and the P5+1 - the United States, France, Britain, Russia, China and Germany - finalised the text of the JCPOA in Vienna, Austria, on July 14, 2015.

Under the agreement, limits are put on Iran’s nuclear activities in exchange for, among other things, the removal of all nuclear-related economic and financial bans against the Islamic Republic.

In another move, Secretary of State John Kerry said Washington is slated to repay Iran a $400 million debt, along with an additional $1.3 billion in interest.

Kerry made the announcement on Sunday, adding the payments date back to the 1979 Islamic Revolution in Iran, according to media reports.

The news comes a day after President Barack Obama signed an executive order, lifting US economic sanctions on Iran.

The repayment, arranged after an international legal tribunal, is separate from the tens of billions of dollars in frozen assets that Tehran can now access.

Secretary Kerry appeared elated by the release of the American prisoners, including Washington Post reporter Jason Rezaian, an issue he took up on the edges of almost every nuclear negotiation, and pursued in separate, secret talks that many involved in the nuclear issue were only vaguely aware were happening.

A senior American official said Saturday that Iran will be able to access about $50 billion of a reported $100 billion in holdings abroad, though others have used higher estimates. The official said Iran will likely need to keep much of those assets abroad to facilitate international trade.

US President Barack Obama defended the debt settlement in a televised statement from the White House, saying it was for "much less than the amount Iran sought."

"For the United States, the settlement could save us billions of dollars that could have been pursued by Iran. There was no benefit to the United States in dragging this out," he said.

Kerry said the claim was in the amount of a $400 million trust fund used by Iran to purchase military equipment from the United States prior to the break in diplomatic ties, plus $1.3 billion in interests.

Iranian-US ties broke down in 1979 after revolutionaries - angered at US support for the Iran's deposed monarch - stormed the American embassy and took hostages.

In 1981, the Iran-US Claims tribunal was established in The Hague to settle outstanding debts between the two countries, and Tehran filed a suit demanding the arms payment be returned.

Kerry described Sunday's payment of the 35-year-old trust as a "fair settlement," but it is sure to draw the ire of those in Washington who think he had already made too many concessions to secure the nuclear deal.

"Iran will receive the balance of $400 million in the Trust Fund, as well as a roughly $1.3 billion compromise on the interest," he said, in a statement.

"Iran's recovery was fixed at a reasonable rate of interest and therefore Iran is unable to pursue a bigger tribunal award against us, preventing US taxpayers from being obligated to a larger amount of money."

Kerry went on to say all of the US claims against Iran at the tribunal had long been settled and had netted American companies and individuals $2.5 billion.

But he added there are more Iranian claims pending and that the United States would try to negotiate to resolve them.

The Obama administration on Saturday also removed 400 Iranians and others from its sanctions list and took other steps to lift selected restrictions on interactions with Iran. Another 200 people, however, will remain on the sanctions list for other reasons, including alleged terrorist activities, human rights abuses, involvement in civil wars in Syria or Yemen or ties to the country’s ballistic missile program.

Under the new rules put in place, the United States will no longer sanction foreign individuals or firms for buying oil and gas from Iran. The American trade embargo remains in place, but the government will permit certain limited business activities with Iran, such as selling or purchasing Iranian food and carpets and American commercial aircraft and parts.