The CIA has a recording of a phone call in which Saudi Crown Prince Mohammed bin Salman gave instructions to “silence Jamal Kashoggi as soon as possible”, Turkish news website Hurriyet Daily News reports.

It cited a prominent Turkish columnist as saying CIA director Gina Haspel had “signalled” the existence of the recording during a visit to Ankara last month.

A Turkish official contacted by Reuters said he had no information about such a recording.

It comes as the EU’s top diplomat Federica Mogherini said on Thursday all those “really responsible” for the journalist’s murder have to be held accountable.

After Saudi Arabia accepted responsibility and said that 21 people were in custody, with death penalties sought against five men, attention turned to whether the crown prince would be found culpable.

“Those responsible, really responsible for this terrible murder have to be accountable,” Mogherini told a news conference in Ankara with Turkish Foreign Minister Mevlut Cavusoglu.

Calling for a “completely transparent and credible investigation”, she said: “For us accountability does not mean revenge.”

Khashoggi, a US resident who wrote for The Washington Post and had been critical of the Crown Prince, was lured to the Saudi consulate in Istanbul on October 2, killed and according to Turkish prosecutors dismembered.

After lengthy denials, Saudi authorities admitted responsibility and said 21 people had been taken into custody.

However, a CIA analysis leaked to the US media went further, reportedly pointing the finger at the Crown Prince.

Turkey has repeatedly called for those who ordered the murder to be held accountable but has stopped short of directly blaming Prince Mohammed.

“We’ve always been against for instance any application of death penalty but we expect in line with our principles, values, practices on judicial systems full investigation, transparent and fair to take place,” Mogeherini said.

Meanwhile, Recep Tayyip Erdogan could meet with Saudi Crown Prince Mohammed bin Salman at the upcoming Group of 20 summit in Buenos Aires later this month.

Presidential spokesman Ibrahim Kalin was asked whether the two could meet at the two-day G-20 summit, which starts on November 30, that “we are looking at the schedule, it is possible.”

His remarks were carried by the state-run Anadolu Agency.

It would be the first official contact between the prince and Mr Erdogan, who has kept international pressure mounting on Saudi Arabia over the killing of Khashoggi.