Current and former United States officials believed that Israel might have been plotting to kill Iran’s top negotiators during sensitive ceasefire talks this spring, the US daily The New York Times reported on Thursday.

The newspaper, citing American officials, said Washington was concerned that Iran’s Foreign Minister Abbas Araghchi and Parliament Speaker Mohammad Bagher Ghalibaf could have been targeted when negotiations intensified in April.

According to the report, the Trump administration was so concerned that it asked other countries in the region to warn Tehran about the possibility that Israel could target the two officials.

Read: Iran warns US, Israel against attacks ahead of funeral processions for Khamenei

US officials reportedly believed any assassination attempt after negotiations began in earnest in April would have ended the talks and reignited the conflict.

The report said Washington learned that at least Ghalibaf had been placed on an Israeli target list and urged Israel not to proceed.

It also cited Iranian officials as saying Tehran sought US guarantees, through Pakistani and Qatari intermediaries, that Israel would not target its negotiating team during diplomatic meetings.

The report detailed an April incident in which Ghalibaf’s return flight from Islamabad diverted to Mashhad after Iranian security forces detected two Israeli jets entering Iranian airspace.

The report said Israeli Embassy officials in Washington declined to comment on the allegations.

A US official told the newspaper that talks between the American and Iranian delegations are continuing and that President Donald Trump wants the peace process “to play out”.