Saudi Arabia on Thursday resisted growing demands for transparency in the trial of government operatives allegedly behind the brutal murder and dismemberment of Washington Post columnist Jamal Khashoggi.

Turkey, where Khashoggi's killing took place, said Interpol had issued "red notices" for 20 suspects at the request of the Istanbul prosecutor pursuing the case. The move is meant to put pressure on Riyadh.

Rejecting growing calls for an international inquiry, president of the Saudi Human Rights Commission Bandar al-Aiban claimed the defendants had been brought to a third hearing after their 3 January indictment.

But Turkey and others have demanded more transparency in a trial that has been largely hidden from public view.

"Shedding light on the incident and bringing to justice all murderers and instigators is a requirement under our international order and a guarantee of the kingdom’s international reputation," said Fahrettin Altun, a spokesperson for Turkish president Recep Tayyip Erdogan, in a statement.

“We urge Saudi Arabia to tell the world which individuals are currently on trial on what charge(s), in order not to raise any questions about the sincerity of the judicial proceedings in the kingdom.”

The Interpol red notices which Turkey has requested do not mean the suspects will be arrested but would complicate their attempts to travel. The EU has in the past criticised Turkey for abusing Interpol by requesting red notices for political dissidents. However, the latest filings are in likely to be in line with western aims to bring a measure of accountability to the Khashoggi killing.

Mr Aiban failed to disclose the exact number of suspects hauled into court and the exact date the third hearing was held. But he did say they attended with their lawyers, with unspecified “non-governmental organisations” observing the proceedings.

He rejected what he called attempts to “internationalise” the murder, a reference to calls by human rights organisations, the UN, and dozens of governments for an independent inquiry into the case.

Jamal Khashoggi death: key figures Show all 7 1 /7 Jamal Khashoggi death: key figures Jamal Khashoggi death: key figures Jamal Khashoggi Washington Post journalist who was critical of the Saudi regime and the young Crown Prince Mohammed bin Salman, he was murdered on 2 October in the Saudi Arabian consulate in Istanbul AFP Jamal Khashoggi death: key figures Saudi Crown Prince Mohammed bin Salman Heir to the Saudi throne, Mohammed bin Salman has been implicated in the murder, with US officials claiming that he must have known of the plot AFP/Getty Jamal Khashoggi death: key figures 15 man hit squad Turkish police suspect these 15 men of being involved in the murder of Jamal Khashoggi, issued 10 October, 8 days after the journalist disappeared EPA Jamal Khashoggi death: key figures Saud al-Qahtani Aide to Crown Prince Mohammed bin Salman, Saud al-Qahtani is claimed to have ordered Khashoggi's murder Saud Al-Qahtani/Twitter Jamal Khashoggi death: key figures Maher Abdulaziz Mutreb A former diplomat who often travelled with the Crown Prince, Mutreb was initially claimed to be the leader of the hit squad and is pictured here entering the Saudi consulate on the day of the murder AP Jamal Khashoggi death: key figures Mustafa al-Madani First implicated in the 15 CCTV photos released by the Turkish police, al-Madani was later found to have been used as a body double for Khashoggi, leaving the Saudi consulate dressed in his clothes on the day the journalist was killed CNN Jamal Khashoggi death: key figures Salah bin Jamal Khashoggi (L) Son of the murdered journalist met with Crown Prince Mohammed bin Salman on 23 October EPA

But in many respects, the case has been an international matter from the start, crossing multiple jurisdictions. Khashoggi, a resident in the US, was murdered in October in his own nation’s Istanbul consulate by a team of killers dispatched from the Saudi capital, Riyadh. His body has yet to be found. The case prompted global outrage and accusations by US officials and Saudi experts that Crown Prince Mohammed bin Salman, an ally and friend of US President Donald Trump and his family, likely ordered the kill, something the royal court has repeatedly denied.

The latest developments in the Khashoggi trial come amid increased pressure on Saudi Arabia and its Crown Prince. The US Senate voted on Wednesday to pull the plug on Washington’s support for Prince Mohammed’s war effort in Yemen, a conflict that has been described as the worst humanitarian crisis in the world. The 54-46 vote included a number of members of Mr Trump’s own Republican Party.

“If they had taken some meaningful step in the Khashoggi situation they might have increased the odds that some of us wouldn’t vote to repudiate their efforts in Yemen, but they’ve done nothing,” said Senator Tim Kaine, a Virginia Democrat, according to political website The Hill. “So that means you’re going to get a lot of votes for the Yemen resolution.”

Meanwhile, the US State Department raised the Khashoggi affair on Wednesday in its annual review of human rights around the world. “Even some of our friends, partners, allies have human rights violations,” said Secretary of State Mike Pompeo at the launch of the report.

The report, without mentioning Prince Mohammed, described how “government agents carried out the killing”. It also took Saudi Arabia to task for failing to name the suspects, describe their alleged roles, or provide details about the investigation.

A western diplomat confirmed to The Independent that an official of their nation attended the first hearing. But neither journalists nor human rights monitors have been able to attend any of the court hearings, and none of the diplomats who have purportedly been allowed inside the courtroom have publicly spoken about the proceedings.