UNITED NATIONS - United Nations Secretary-General Ban Ki-moon has received a letter from Iran urging him to convince the United States to stop violating state immunity after the top US court ruled that $2 billion in frozen Iranian assets must be paid to American victims of attacks blamed on Tehran, a UN spokesman said Friday.

“The letter will be studied. Of course, the secretary-general’s good offices are available to all parties,” Spokesman Stephane Dujarric said in response to a question at the daily news briefing. Iran’s Foreign Minister Mohammad Javad Zarif wrote to the UN chief a week after the US Supreme Court ruling, calling on the Secretary-General to use his “good offices in order to induce the US Government to adhere to its international obligations.”

Zarif’s appeal comes amid increasing Iranian frustration at what they say is the failure of the United States to keep its promises regarding sanctions relief agreed under an historic nuclear deal struck last year by Tehran and six world powers.

In the letter, released by the Iranian UN mission, Zarif asked Ban to help secure the release of frozen Iranian assets in US banks and persuade Washington to stop interfering with Iran’s international commercial and financial transactions. “The US Executive branch illegally freezes Iranian national assets; the U.S Legislative branch legislates to pave the ground for their illicit seizures; and the US Judicial branch issues rulings to confiscate Iranian assets without any base in law or fact,” Zarif said.

Supreme Leader Ayatollah Ali Khamenei’s top adviser Ali Akbar Velayati was quoted by Iranian state media as saying that “Iran will never abandon its right and will take any necessary action to stop such an international theft.” “This money belongs to Iran,” he said.

Zarif told Ban he wanted to “alert you and through you the U.N. general membership about the catastrophic implications of the U.S. blatant disrespect for state immunity, which will cause systematic erosion of this fundamental principle.” The US Supreme Court found that the U.S. Congress did not usurp the authority of American courts by passing a 2012 law stating that Iran’s frozen funds should go toward satisfying a $2.65 billion judgment won by the U.S. families against Iran in U.S. federal court in 2007.

“It is in fact the United States that must pay long overdue reparations to the Iranian people for its persistent hostile policies,” Zarif wrote, citing incidents including the shooting of an Iranian civil airliner in 1988. Last week Zarif met several times with U.S. Secretary of State John Kerry in New York to discuss Iranian problems accessing international financial markets.

Moreover, UN Secretary-General Ban Ki-moon is ready to help settle a dispute between Iran and the United States on Tehran’s frozen assets, but only if both countries make that request, a UN spokesman said Friday. Iranian Foreign Minister M Javad Zarif called on Ban to use his “good offices” to press the United States to release all frozen assets in US banks, in a letter sent Thursday. “The secretary-general’s good offices are always available should both parties to whatever tensions or issue request it,” UN spokesman Stephane Dujarric said.

Zarif wrote to Ban in response to a US Supreme Court decision last week that said Tehran’s frozen assets can be used to compensate victims of terror attacks. The foreign minister called the ruling “outrageous robbery disguised under a court order” and warned that Tehran reserves the right to take “counter-measures”.

The Supreme Court ruled on April 20 that Iran must hand over nearly $2 billion in frozen assets to the more than 1,000 survivors and relatives of those killed in attacks blamed on Tehran. The attacks included the 1983 bombing of US Marine barracks in Beirut and the 1996 Khobar Towers bombing in Saudi Arabia. “It is in fact the United States that must pay long overdue reparations to the Iranian people for its persistent hostile policies,” wrote Zarif.

He cited US involvement in the 1953 Iran coup, US backing for Baghdad in the Iran-Iraq war and the shooting down of an Iranian airliner by a US missile in 1988 as grounds for US compensation to Iranian nationals. Under a historic deal reached last year on curbing Iran’s nuclear program, tens of billions of dollars in frozen Iranian assets are to be released. The Supreme Court ruling came after a New York tribunal in March ordered Tehran to pay $7.5 billion to victims of the September 11, 2001 attacks on the World Trade Center and the Pentagon — and $3 billion to insurers over related claims — after ruling that Iran had failed to prove that it did not help the bombers. Zarif called the claim of Iranian involvement in the 9/11 attacks “absurd,” saying it contradicts “even public statements as well as findings — open or sealed — of investigations by the US government and US Congress.”