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

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 as of February 19, Iran’s total enriched uranium stockpile amounted to 1,020.9 kilograms (1.1 tons), compared to 372.3 kilograms noted in its last report on November 3, 2019.

The nuclear deal that Iran signed in 2015 with the United States, Germany, France, Britain, China and Russia allows Iran only to keep a stockpile of 202.8 kilograms.

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The deal promised Iran economic incentives in return for the curbs on its nuclear program, but since US President Donald Trump pulled the United States out of the deal unilaterally in 2018, however, Iran has been slowly violating the deal’s restrictions. With the violations, 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 American withdrawal.

In a second report issued 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. It said it had sent questions to Iran in three separate letters but received no answers.

“The agency identified a number of questions related to possible undeclared nuclear material and nuclear-related activities at three locations in Iran that had not been declared by Iran,” the agency said in the report.

The IAEA had previously said that uranium particles of man-made origin had been discovered at one location outside Tehran that had not been declared, which appeared to confirm allegations made by the US and Israel about a secret nuclear warehouse.

The agency said Tehran responded to its latest concerns in a letter on January 28 that “Iran will not recognize any allegation on past activities and does not consider itself obliged to respond to such allegations.”

The IAEA responded that its requests for clarification were in line with Iran’s broader commitment to allow inspections of its nuclear facilities and not tied in to the landmark nuclear deal with world powers.

Also Tuesday, the head of the IAEA sounded the alarm on Iran’s nuclear program and demanded “clarifications” over an undeclared site in Tehran where uranium particles were found late last year.

Rafael Grossi, who was in Paris to meet French President Emmanuel Macron, told AFP: “Iran must decide to cooperate in a clearer manner with the agency to give the necessary clarifications.”

“The fact that we found traces (of uranium) is very important. That means there is the possibility of nuclear activities and material that are not under international supervision and about which we know not the origin or the intent.

“That worries me,” Grossi added.

The IAEA has for months been pressing Tehran for information about the kind of activities being carried out at the undeclared site where the uranium particles were found.

While the IAEA has not identified the site in question, diplomatic sources told AFP the agency asked Iran about a site in the Turquzabad district of Tehran, where Israel has alleged secret atomic activity in the past.