ISTANBUL — Istanbul’s top prosecutor on Wednesday filed arrest warrants for two senior Saudi officials who are close to the Saudi crown prince, accusing them of masterminding the killing of the dissident Jamal Khashoggi, according to a senior Turkish official familiar with the investigation and state-run media.

The two Saudis, Maj. Gen. Ahmad al-Assiri and Saud el-Qahtani, are both close aides of Prince Mohammed bin Salman, the de facto ruler of the kingdom and designated heir to the throne, and Western and Turkish officials have said that Mr. Khashoggi’s killing could not have been conducted without the crown prince’s knowledge and approval.

Mr. Khashoggi, a Saudi citizen who lived in the United States and wrote opinion columns for The Washington Post, was killed and his body dismembered inside the Saudi Consulate in Istanbul on Oct. 2. The killing has prompted international outrage over the kingdom’s tactics, and the top United Nations human rights official repeated her call for an international investigation on Wednesday.

The Turkish official, speaking on condition of anonymity according to the protocol of his office, said the arrest warrants were filed after Turkey concluded that the Saudis would not take any formal action against the men.

The Saudis have detained as many as 18 people in connection with Mr. Khashoggi’s death, according to Saudi media reports, but General Assiri and Mr. Qahtani are not among them.

Turkish officials have steadily leaked information to the media throughout the investigation as a way of maintaining pressure on Saudi authorities without causing a diplomatic break in relations. While the arrest warrants will help Turkey keep the case in the public eye, officials in Riyadh are unlikely to turn the two suspects over to the Turks.

General Assiri, who previously served as the spokesman for the Saudi-led military intervention in Yemen, is a high-ranking adviser to Prince Mohammed, and he would have had both access to the crown prince and the authority to deploy lower-ranking personnel.

Mr. Qahtani, like General Assiri, is a close adviser to the crown prince and is among those targeted by the United States for sanctions in response to the killing of Mr. Khashoggi. When the leader of the hit team was recorded by Turkish intelligence saying “tell your boss” that the mission was complete, he was believed to have been communicating with Mr. Qahtani.

A bipartisan group of United States senators said on Tuesday that a classified briefing by the C.I.A. director, Gina Haspel, had only solidified their belief that Prince Mohammed had ordered the killing of Mr. Khashoggi, 59.

The Saudi authorities initially denied that Mr. Khashoggi, a critic of the kingdom under Prince Mohammed, had been harmed in the consulate. After issuing several different accounts, the Saudis acknowledged that he had been killed after what they described as a botched attempt to force him to return to Saudi Arabia.

Turkish officials have insisted that the killing was premeditated. The body has not been found.

“In light of information obtained by the judicial authorities of the Kingdom of Saudi Arabia as part of the investigation, there is strong suspicion that Ahmad al-Assiri and Saud al-Qahtani were among the planners of the incident,” the acting chief prosecutor, Hasan Yilmaz, said in the application for the arrest warrants.

The Turkish official familiar with the investigation said that the phrase “among the planners” indicated that the list was not necessarily final.

The official said that sending the suspects to Turkey would allow it more fully to investigate the case, and he reiterated Turkey’s frustration with what it says is a lack of cooperation from Saudi Arabia. The Saudis have yet to say what happened to Mr. Khashoggi’s remains or who ordered and organized his killing, or to identify the “local collaborator” who Saudi officials have said helped dispose of the body.

The United Nations human rights chief, Michelle Bachelet, repeated her call for an international investigation into the murder of Mr. Khashoggi and said she had told the secretary general, Antonio Guterres, that such an inquiry is justified.

“I do believe it is really needed in order to identify the facts of what occurred and who was responsible for that awful killing,” Ms. Bachelet, the high commissioner for human rights, told journalists in Geneva.

Her office does not have a mandate to conduct a criminal investigation, Ms. Bachelet said, and it had not received the information that Turkey has shared with other countries.