The US House of Representatives has passed legislation barring dozens of tons of heavy water to be purchased from Iran as part of a landmark nuclear deal, despite President Obama’s threats the law will be vetoed to keep the agreement with Tehran in place.

The legislation was passed on Wednesday by 249-176, with support mostly coming from the Republican majority.The ‘No 2H2O from Iran Act’ literally prohibits purchase or licensing of the purchase of heavy water produced in Iran.

Heavy water is an important by-product of producing nuclear weapons and energy, but it is not radioactive. In April, the US Department of Energy said it will buy 32 metric tons of heavy water from Iran worth $8.6 million.

Paul Ryan, the speaker of the House of Representatives, said at that time the announcement was "another unprecedented concession to the world's leading state-sponsor of terrorism."

The Congress Republicans have long described the heavy water purchase a subsidy to Iran’s nuclear program, triggering the White House’s response on Monday when it threatened to veto the bill.

Representative Ed Royce, chairman of the House’s Foreign Affairs Committee, denied that the legislation would violate the nuclear deal whatsoever, insisting “it would deter Iran from producing heavy water by making its sale more difficult,” according to Reuters.

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In addition, Republicans Bob Corker, chairman of the Senate Foreign Relations Committee, and Marco Rubio, as well as Democrats Robert Menendez and Joe Manchin said on Wednesday they would introduce a separate Iran-related bill.

The proposal introduced by the lawmakers seeks to expand sanctions against Iran's ballistic missile projects, sanction transfers of conventional weapons to or from Iran and extend the Iran Sanctions Act which expires by the end of 2016, according to Reuters.

Under the landmark nuclear agreement sealed by the US, UK, France, China, Russia and Germany, Tehran has to significantly reduce its stockpiles of heavy water. The deal permits Iran to keep up to 130 tons at present and up to 90 tons once the nuclear research reactor in Arak is re-designed and commissioned.

Excessive stock of the heavy water as well as enriched uranium could be diluted, deposed or sold on the international market.

Thursday’s vote follows previous moves, which have aggravated US relations with Iran. In April, the US Supreme Court ruled that Iranian assets worth $2 billion must be paid to American families of those killed in 1983 military attacks in Beirut.

Washington has put the blame on the militant group Hezbollah that was reportedly financed by Iran. Both Tehran and Hezbollah have denied being responsible for the attacks.

Iranian President Hassan Rouhani, who proactively pushed for the nuclear deal, promised Tehran will take matters to court.

“The Islamic Republic of Iran officially complained about America to the International Court of Justice for the confiscation and theft of $2 billion,” he was quoted as saying by Reuters in June.