Iran will finalize its fifth step back from a nuclear deal on Sunday, a spokesman said, in retaliation for the U.S. withdrawing from the multilateral accord and reimposing sanctions. 

"Regarding the fifth step, decisions had already been made... but considering the current situation, some changes will be made in an important meeting tonight," foreign ministry spokesman Abbas Mousavi said in televised remarks, two days after the U.S. killed a top Iranian general in a drone strike.  

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The announcement came against the backdrop of the U.S. killing of Qasem Soleimani that has sparked outrage in Iran, which has vowed to retaliate, with the international community is calling for restraint to avoid a further escalation of tensions in the Gulf region. 

"In the world of politics, all things affect each other," he added. Mousavi gave no indication as to what the next step would be nor when it would be announced.

The nuclear accord between Iran and the United Nations Security Council's five permanent members – Britain, China, France, Russia and the United States, plus Germany was agreed in 2015.

The agreement, known as the Joint Comprehensive Plan of Action (JCPOA), has been unraveling since the unilateral withdrawal of the United States last year and the reimposition of American sanctions, which have left Iran's economy struggling. 

In response, Iran has recently exceeded the stockpiles of uranium and heavy water allowed by the deal and has started enriching uranium at a purity level beyond what is permitted. 

(With input from AFP)