A UN official investigating the murder of journalist Jamal Khashoggi was unable to examine the Saudi consulate where he was killed despite requesting access to the crime scene, prompting Turkish officials to add pressure on Riyadh.

The UN special rapporteur on extrajudicial executions, Agnes Callamard, arrived in Turkey on Monday for a week-long visit to kick off her investigation of the murder. She told journalists she sought to enter the consulate in Istanbul where Khashoggi was murdered but has not been given permission to do so.

“We are respectfully calling on the authorities to give us access at some stage,” she said, according to news agencies, conceding that she had submitted her request “quite late” and was willing to allow Saudi authorities time to respond.

But Turkish officials demanded she be allowed in.

“The fact that this rapporteur has not been accepted in is scandalous,” Omer Celik, spokesperson for Turkey’s ruling Justice and Development party, said in a television interview. “It is an approach that shows there is no cooperation and something is being concealed.”

Ms Callamard, heading a team that includes a UK barrister and a Portuguese forensic pathologist, may not find any new evidence in the building, which has already been examined by Saudi and Turkish investigators.

But a visit to the consulate may give her a sharper picture of what unfolded inside the facility on 2 October, when members of a kill squad dispatched from Riyadh brutally murdered and dismembered the journalist after he was lured inside.

Saudi Arabia insists that rogue senior intelligence and security officials close to the country’s de facto ruler, Crown Prince Mohammad bin Salman, concocted the scheme to kill Khashoggi, a Washington Post contributor, on their own, handing his corpse off to a “local collaborator” who disposed of it.

Riyadh claims it is prosecuting or investigating nearly two dozen men allegedly connected to the killing, but has presented to evidence of a court proceedings or named any suspects. It has rejected Turkey’s demand to extradite the suspects to be tried under Turkish law.

Many international human rights and press freedom groups suspect Riyadh is attempting to sweep the Khashoggi matter under the rug in order to continue pursuing big business deals with western partners spooked by the widespread outcry over the killing, which became a global symbol of declining civil liberties and increasing impunity by autocrats.

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

Ms Callamard has until June to investigate the case and present her findings to the UN Human Rights Council.

Turkey has embraced Ms Callamard’s probe. On Monday she met with Turkey’s foreign minister Mevlut Cavusoglu and justice minister Abdulhamit Gul in Ankara, and an on Tuesday with Istanbul chief prosecutor Irfan Fidan who is heading the investigation.