TEHRAN — The Iranian authorities have arrested four people suspected of planning to sabotage one of the country’s nuclear sites, the chief of Iran’s nuclear program told reporters on Sunday.

The nuclear chief, Ali Akbar Salehi, who was foreign minister for three years under the previous president, Mahmoud Ahmadinejad, warned that “some countries” are “not happy” now that Iran is trying to reach a settlement with the West in the 10-year-long nuclear standoff.

“They are implementing sabotage plots,” Mr. Salehi said, according to the conservative Tasnim news agency. He did not elaborate further.

The four arrested were most likely employees of Iran’s nuclear program, as Mr. Salehi said that they had been working inside unspecified nuclear facilities. “Of course, these people were under our control from the very beginning, but we allowed them to proceed a bit and arrested them right on time,” Mr. Salehi said, adding that “a couple of sabotage acts had been foiled.”