According to reports, Tehran is only ready to agree to a five-year pause on its nuclear energy program

A 20-year uranium enrichment moratorium on Iran is not long enough, US President Donald Trump has claimed.

Trump was responding to reports that the US delegation at talks with Iran, led by Vice President J.D. Vance, had proposed a 20-year ban on Tehran pursuing its nuclear program.

At the discussions in Islamabad, which finished without any breakthrough, Iran reportedly offered a five-year moratorium. Tehran's negotiators also rejected Washington's call to confiscate Iran's stockpile of enriched uranium, believed to be about 440 kg (970 pounds).

"I've been saying they can't have nuclear weapons, so I don't like the 20 years," Trump said in an interview with the New York Post on Tuesday.

Iran has said repeatedly over the years that it is not looking to obtain a nuclear bomb, but it also insists on its right to enrich uranium for peaceful purposes.

When asked if a shorter moratorium could become the "win" that the authorities in Tehran need to present to the people in order to be able to sign a deal with Washington, the president replied by saying: "I don't want them [Iran] to feel like they have a win."

The Iranian consul general in Mumbai, Saeid Reza Mosayeb Motlagh, told RT on Tuesday that there is "a deep mistrust" in Tehran towards Washington, but despite this fact, the Islamic Republic "remains ready to negotiate... provided the discussions are realistic."

Iran's nuclear program "never deviated toward military purposes," which was proven by "the most stringent inspections of our nuclear facilities," he said.

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In Beijing on Wednesday, Russian Foreign Minister Sergey Lavrov stressed that Tehran has "an inalienable right" to enrich uranium for peaceful purposes.

Any decision by Tehran on the issue - whether it pauses enrichment or insists on continuing it - "will be accepted by the Russian side," he stressed.

Lavrov also expressed hope that the Americans "will be realists" during the negotiating process and "will not continue the unprovoked aggression" against Tehran, which affects the entire Middle East.