A United Nations investigation team held contacts in Turkey this week for a first inquiry of international nature into the brutal killing of the Saudi journalist Jamal Khashoggi nearly four months ago inside the Saudi Consulate in Istanbul.

The visit of Agnes Callamard, the UN special rapporteur on extrajudicial, summary or arbitrary executions, to Turkey is the first probe of the murder by an international official as Turkish authorities are pushing for an advanced investigation.

Experts believe that the UN envoy's visit is the result of Turkey's efforts to maintain the case of the slain journalist in the international community's agenda.

"Turkey's arguments for the need of an international inquiry over this shocking murder seem to be accepted by the UN envoy amid Saudi Arabia's uncooperative approach in aiding the investigation," Selcuk Colakoglu, director of the Ankara-based Turkish Center for Asia-Pacific Studies said.

"Turkey's motivation stems from the fact that the murder happened on its sovereign territory and it is a matter of prestige to get to the bottom of it," pointed out Colakoglu, a professor of international relations.

Turkey has been outraged over the use of a diplomatic mission as a torture chamber as leaks from Turkish officials to local news outlets suggested that Khashoggi was strangled after he entered the compound.

The French official and her team met with Turkish Foreign Minister Mevlut Cavusoglu in Ankara on Monday and then flew to Istanbul to convene on Tuesday with chief prosecutor Irfan Fidan. The meetings were closed to the press and Callamard denied interview requests.

On Wednesday, however, Callamard, an independent expert appointed by the UN, spoke to journalist outside the Saudi consulate where she was denied entry the day before, and said her report would be made public in time for the June session of the UN human right council.

Callamard told reporters at the end of her mission in Istanbul that she was "disappointed" not to be permitted to enter the Saudi complex to see for herself where the gruesome murder took place.

Omer Celik, spokesman for Turkey's ruling Justice and Development Party (AKP), blasted the Saudi failure to respond to the UN delegation request as a "scandal."

Before her week-long visit, the UN official said the inquiry was her own initiative, independent of the UN or any government. Turkey, however, had repeatedly called for an international investigation into the killing because of frustration at Saudi Arabia's failure to cooperate and inaction on a joint inquiry.