Iran’s top leader said Wednesday that his country would keep negotiating with world powers over how to salvage the 2015 nuclear deal, quashing speculation that Iran’s delegation would boycott or quit participating in protest of the apparent Israeli sabotage of a major uranium enrichment site this past weekend.

The declaration by the top leader, Ayatollah Ali Khamenei, who has the last word on security matters in the country of 80 million, came three days after an explosive blast at the Natanz enrichment site plunged the heavily guarded facility into a blackout and disabled or destroyed hundreds of underground centrifuges used to process uranium into fuel.

Suspicion for the destruction immediately fell on Israel, which has sabotaged the Natanz site before. Israel neither confirmed nor denied the accusation but intelligence officials said it was a clandestine Israeli operation.

Outraged and embarrassed over such a security lapse, Iran vowed on Tuesday to triple its uranium enrichment purity — the most brazen departure yet from its commitments under the nuclear deal.

also said they would resume, at 12:30 p.m. local time on Thursday.

The discussions, which began early this month and recessed last Friday, are intended to map out a plan for the return of both Iran and the United States to compliance with the deal, which has teetered on collapse since President Donald J. Trump abruptly withdrew the United States from it three years ago.

Twitter that process could begin soon.

Iran has said that all of its departures from compliance with the nuclear agreement could be easily and quickly reversed when the United States rescinds its sanctions.

carried out a series of raids and attacks targeting Iran’s nuclear scientists and its uranium enrichment facilities.

Although American and Israeli governments have collaborated before to counter what they see as Iran’s militaristic nuclear ambitions, Washington denied any role in Sunday’s blackout. The Biden administration has said it remains committed to reviving the nuclear agreement.

Iran and the United States have not been negotiating directly in the talks in Vienna, which are led by the European Union. Instead the other participants in the 2015 accord — Britain, China, France, Germany and Russia — are acting as intermediaries.

Before the blackout at Natanz, European officials maintained that both Iran and the United States were invested in the success of the talks.

The foreign ministries of Germany, France and Britain issued a joint a statement on Wednesday condemning Iran’s uranium enrichment intentions and said that they “reject all escalatory measures by any actor.”

“This is a serious development since the production of highly enriched uranium constitutes an important step in the production of a nuclear weapon,” the statement read. “Iran has no credible civilian need for enrichment at this level.”

The talks adjourned on a positive note last week. They were scheduled to continue this week after all parties agreed to move forward.