TEHRAN, Iran >> Iran announced Sunday it will raise its level of uranium enrichment, breaking another limit of its unraveling 2015 nuclear deal with world powers and further heightening tensions between Tehran and the U.S.

Officials told a news conference the new level would be reached later Sunday, but did not provide a percentage. Government spokesman Ali Rabiei said the new level “will be based on our needs.” Under the faltering nuclear deal, the cap for enrichment had been set at 3.67%.

The officials suggested the latest steps did not close the door to diplomatic efforts to save the deal. “Opportunity will be available for diplomacy,” said Abbas Araghchi, the deputy foreign minister.

French President Emmanuel Macron spoke to his Iranian counterpart, Hassan Rouhani, by phone Saturday, saying he is trying to find a way by July 15 to resume dialogue between Iran and Western partners.

Araghchi, said Sunday that discussions with the Europeans are continuing.

“From our point of view if the U.S. wants to participate in talks between Iran and 4+1 countries, it is possible,” he said, referring to the European parties to the deal.

Yet hopes for saving the faltering deal appear increasingly dim, as the Europeans have been unable to offer Iran any effective way around U.S. sanctions.

While the Iranian steps are concerning to nuclear non-proliferation experts, they could be easily reversible if Europeans offer Iran the sanctions relief it seeks.

Iran’s decision came a year after President Donald Trump unilaterally withdrew from the deal. Iran has repeatedly warned Europe in recent weeks that it would begin walking away from an accord neutered by a maximalist American campaign of sanctions that blocked Tehran’s oil sales abroad and targeted its top officials.

Sunday’s announcement came less than a week after Iran acknowledged breaking the deal’s 300-kilogram (661-pound) limit on its low-enriched uranium stockpile.

Experts warn higher enrichment and a growing stockpile narrow the one-year window Iran would need to have enough material for an atomic bomb, something Iran denies it wants but the deal prevented.

Tensions began rising in May when the U.S. rushed thousands of additional troops, an aircraft carrier, nuclear-capable B-52 bombers and advanced fighter jets to the Mideast. Mysterious oil tanker blasts near the Strait of Hormuz, attacks by Iranian-backed rebels in Yemen on Saudi Arabia and Iran shooting down a U.S. military drone have raised fears of a wider conflict engulfing a region crucial to global energy supplies.

Under the 2015 atomic accord, Iran agreed to enrich uranium to no more than 3.67%, which is enough for peaceful pursuits but is far below weapons-grade levels of 90%.

Iran denies it seeks nuclear weapons, but the nuclear deal sought to prevent that as a possibility by limiting enrichment and Iran’s stockpile of uranium to 300 kilograms (661 pounds).

Iran’s foreign minister is to inform European Union leaders of the decision concerning uranium enrichment, officials said Sunday.

The spokesman for Iran’s nuclear department, Behrouz Kamalvandi, said Sunday that technical preparations for the new level of enrichment will be completed “within several hours and enrichment over 3.67% will begin.”

He says monitoring will show the increased level by Monday morning.