TEHRAN - Iranian Foreign Minister Seyed Abbas Araghchi on Wednesday received a letter from US President Donald Trump on nuclear negotiations, Iran's semi-official Fars news agency reported.

The letter, which reportedly calls for negotiations on Tehran's nuclear program, was handed over to Araghchi by Anwar Gargash, diplomatic advisor to the president of the United Arab Emirates (UAE), in the presence of some other Iranian officials, Fars reported.

According to a report by the semi-official Tasnim news agency, Araghchi said earlier on Wednesday that Iran had always been ready to hold negotiations over its nuclear issue on equal terms.

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Iran previously held talks on the revival of a 2015 nuclear deal, and is continuing dialogue in that regard, Araghchi said, noting that it is the United States that withdrew from the deal.

Iran is holding talks with France, Britain and Germany on a number of issues, including the nuclear one, and a new round of talks will start soon, he said, adding that the country is holding negotiations with other international stakeholders concurrently.

Araghchi said that Iran's nuclear program operates within the framework of the Non-Proliferation Treaty, and that it is completely dynamic and making progress.

In an interview with Fox Business Network on Friday, Trump said he wanted to negotiate with Iran on the nuclear issue and had sent a letter to the country's leadership.

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Iran signed a nuclear deal, formally known as the Joint Comprehensive Plan of Action, with six major countries -- Britain, China, France, Germany, Russia, the United States -- in July 2015, accepting restrictions on its nuclear program in return for sanctions relief.

However, during Trump's first term of office, the United States withdrew from the deal in May 2018 and reinstated sanctions, prompting Iran to scale back some of its nuclear commitments.

Efforts to revive the nuclear deal have not achieved substantial progress. Iranian officials have repeatedly stressed that the country would not negotiate with the United States under pressure and sanctions.  

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Also on Wednesday, Fars reported that Iran confirmed the existence of high-purity lithium reserves in the country.

The confirmation was made in a report by Iran's Ministry of Industry, Mine and Trade, following a one-year sample study on 46 stations in Iran's underground brine reservoirs in the provinces of Qom, Isfahan and Semnan, with advanced technologies, Fars said.

The samples were collected from wells dug with depths of up to 2 meters in Iran's salt pans, and then analyzed jointly by Iran Mineral Processing Research Center and a Russian lab, Fars said.

The study found that the highest purity level of lithium was found in samples taken from the Namak Lake in Qom, with 81.4 parts per million, Fars said.

Lithium is one of the key components in electric vehicle batteries.