JERUSALEM — An Iranian scientist working at a key nuclear facility in that country was killed Wednesday in Tehran, the latest act in what appears to be a widening covert effort to disrupt Iran’s nuclear program.

Mostafa Ahmadi Roshan, a chemistry expert and senior official at the Natanz uranium enrichment facility in central Iran, died when a magnetic bomb was attached to his car by two assailants on a motorcycle, according to Iran’s state news agency, IRNA. Roshan had “organizational links” to Iran’s nuclear agency, including a key role in aspects of the nuclear program, IRNA said.

Israel was immediately suspected of carrying out the attacks. Israeli officials would not confirm or deny whether their agents were involved, but a senior military official who spoke on the condition of anonymity because of the subject offered his approval. “Whoever carried out this attack, there is no doubt that it is positive, and should be seen as such,” the official said.

Israeli military spokesman Brig. Gen. Yoav Mordechai offered a similar view on his Facebook page: “I don’t know who took revenge on the Iranian scientist, but I am definitely not shedding a tear.”