Iran has nearly tripled its stockpile of enriched uranium since November in violation of its deal with world powers and is refusing to answer questions about three possible undeclared nuclear sites, the UN atomic watchdog agency has said.

The International Atomic Energy Agency made the statement in a confidential report distributed to member countries that was seen by the Associated Press.

The agency said that as of 19 February, Iran’s total stockpile of low-enriched uranium amounted to 1,021kg, compared with 372kg noted in its last report on 3 November 2019.

The stockpile puts Iran within reach of the amount needed to produce a nuclear weapon, which it insists it does not want to do.

The nuclear deal that Iran signed in 2015 with the US, Germany, France, Britain, China and Russia, known as the Joint Comprehensive Plan of Action (JCPOA), allows it to keep a stockpile of just under 203kg.

The JCPOA promised Iran economic incentives in return for curbs on its nuclear programme, but since Donald Trump unilaterally pulled the US out of the deal in 2018, Iran has been slowly violating the deal’s restrictions. Tehran has said it hopes to put pressure on the other nations involved to increase economic incentives to make up for hard-hitting sanctions imposed by Washington after the US withdrawal.

In a second report issued on Tuesday, the IAEA said it had identified three locations in Iran where the country possibly stored undeclared nuclear material or undertook nuclear-related activities without declaring it to international observers.

According to the Washington-based Arms Control Association, Iran would need roughly 1,050kg of low-enriched uranium — under 5% purity — and would then need to enrich it further to weapons-grade, or more than 90% purity, for a weapon.

With the nuclear deal in place, Iran’s so-called “breakout time” – the period Tehran would need to build a bomb if it chose – stood at about a year. As Iran has stepped away from the limits of the 2015 nuclear deal, it has slowly narrowed that window.

Before the nuclear deal, Iran enriched its uranium up to 20%, a short technical step away from weapons-grade levels of 90%. In 2013, Iran’s stockpile of enriched uranium was more than 7,000kg with higher enrichment, but it did not pursue a bomb.

Iran has been violating other restrictions in the JCPOA, including the stock of heavy water it is allowed and the number and type of centrifuges it operates. It has announced the violations as they have occurred, and allowed IAEA inspectors access to verify them, saying the measures are all reversible if it gets the economic incentives it needs.﻿