Tehran takes Washington to The Hague in 'terror-compensation' fight

Tehran filed its case to the International Court of Justice on Tuesday, arguing it was "entitled to immunity from the jurisdiction of the US courts", the tribunal said in a statement.

President Hassan Rouhani confirmed: "Iran has officially lodged a complaint with the international court and we will pursue our case until we get a result.

"The American courts have illegally decided that these funds must be given to Americans and the families of victims killed in Lebanon," he said, according to Iranian media.

"It remains unclear what these Americans were doing in Lebanon, and how this affair concerns Iran."

In April, the US Supreme Court ruled 6-2 that victims and relatives affected by several attacks that Washington has linked to Iran must be compensated using $2 billion worth of frozen assets.

This includes the 1983 bombing of a US Marine barracks in Beirut - killing 241 US troops - and the 1996 Khobar Towers bombing in Saudi Arabia - which left 19 Americans dead, along with other attacks blamed on Iran.

The decision affects more than a thousand Americans who are expected to receive the funds "promptly", according to Matthew McGill, a partner at Olson's firm.

Iran has maintained the law is unconstitutional as it violated separation of powers, but federal courts rejected that claim.

The court's decision comes as the long-term foes hope for better relations after a nuclear deal between Iran, the United States and five other major powers was agreed last year.

It also coincides with a controversial bill which could allow families of the 11 September 2011 attacks to sue the Saudi government in US courts for its alleged link to the attack that left nearly 3,000 people dead.