Saudi Arabia's consulate in Istanbul, Sunday, Oct. 28, 2018. (Lefteris Pitarakis/AP)

Turkey’s foreign minister warned Saudi Arabia on Monday against prolonging an inquiry into Jamal Khashoggi’s slaying, urging the kingdom to accept its “very large” responsibility in investigating the writer’s death as the Saudi chief prosecutor arrived in Istanbul for talks.

Saud al-Mojeb, who is leading the Saudi government’s inquiry, met with his Turkish counterpart for the first time Monday, Turkey’s state-run news agency reported. The outcome of the talks was not immediately clear.

A team of 15 Saudi agents was involved in the killing of Khashoggi — a Washington Post contributing columnist — inside the Saudi Consulate in Istanbul this month, Turkish officials have concluded, calling it a premeditated crime.

Turkey, through a gradual release of information and public statements, has helped feed an international outcry over the case and pressured Saudi Arabia to concede its role.

Mojeb’s arrival in Istanbul was the latest step in a high-stakes investigation that could implicate members of the Saudi leadership and potentially reshape the region’s politics.

Turkish investigators have reviewed thousands of hours of closed-circuit-television footage, taken forensic samples from the consulate grounds and released details of the passports of the 15 Saudis they say were involved.

Turkey also played a purported audio of the killing for CIA Director Gina Haspel last week.

“The responsibility of Saudi Arabia is very large here,” Foreign Minister Mevlut Cavusoglu said at a news conference Monday, adding that Khashoggi’s remains have not been found.

“This cooperation must continue,” Cavusoglu said of the meeting between the two countries’ prosecutors.

But the investigation “should not be prolonged,” he said. “All the facts should be revealed.”

Khashoggi entered the consulate around 1 p.m. Oct. 2 to retrieve paperwork for his upcoming marriage to his Turkish fiancee, Hatice Cengiz.

He had fled Saudi Arabia and taken up residence in the United States, where he wrote columns for The Post. He was a critic of Crown Prince Mohammed bin Salman, the de facto Saudi ruler, who has purged rivals and consolidated power.

Turkish investigators say Khashoggi was murdered and then dismembered.

In response to the uproar, Saudi authorities arrested 18 suspects, fired five officials and ordered a reorganization of the nation’s intelligence agency. Turkey has called on Saudi Arabia to extradite the 18 suspects as part of the investigation.

At a memorial service Monday night in London, Cengiz said she never imagined such barbarity was awaiting Khashoggi inside the consulate.

“They took the body of Jamal from me,” she said. “I want justice for my beloved Jamal. I want to hug his body. . . . We still do not know where his body is.”

Cengiz had tough words for both Saudi Arabia and the United States.

“I believe the Saudi regime knows where his body is,” she told the audience at the service, sponsored by the Middle East Monitor and Al Sharq Forum. “I want justice to be served not only for those who murdered Jamal but those who ordered his murder.”

She added, “President Trump should not pave the way for a coverup.”

William Booth in London contributed to this report.