A Saudi consulate worker in Istanbul has told a Turkish court he had been asked to light a tandoor oven less than an hour after Saudi journalist Jamal Khashoggi entered the building where he was killed.

Zeki Demir, a local technician who worked for the consulate, was giving evidence on the first day of the trial in absentia of 20 Saudi officials over Khashoggi’s killing, which sparked global outrage and tarnished the image of Saudi Arabia’s de facto ruler.

Mr Demir said he had been called to the consul’s residence after Khashoggi entered the nearby consulate to seek his papers.

“There were five to six people there… They asked me to light up the tandoor (oven). There was an air of panic,” he said.

Khashoggi disappeared after going to the consulate to get papers for his marriage in October 2018.

Khashoggi’s fiancee Hatice Cengiz waited unknowing outside the consulate while, according to prosecutors, he was suffocated and his body was dismembered.

Some intelligence agencies including the CIA have said they believed Saudi Crown Prince Mohammed bin Salman had ordered the hit – an accusation Saudi officials denied.

Turkish officials have said one theory police pursued was that Khashoggi’s killers may have tried to dispose of his body by burning it after suffocating him and cutting up his corpse.

The indictment accuses two top Saudi officials, former deputy head of Saudi Arabia’s general intelligence Ahmed al-Asiri and former royal court adviser Saud al-Qahtani, of instigating “premeditated murder with monstrous intent”.

It says 18 other defendants were flown to Turkey to kill Khashoggi, a prominent and well-connected journalist who had grown increasingly critical of the crown prince.

According to his testimony in the indictment, Mr Demir reported seeing many skewers of meat and a small barbecue in addition to the oven in the consul’s garden.

Marble slabs around the oven appeared to have changed colour as if they had been cleaned with a chemical, the indictment reported him as saying.

Separate witness testimony in the indictment, from the consul’s driver, said the consul had ordered raw kebabs to be bought from a local restaurant.

Mr Demir offered to help with the garage door when a car with darkened windows arrived, but he was told to leave the garden quickly, the indictment said.

Khashoggi’s fiancee Hatice Cengiz said she would continue to seek justice “not only in Turkey but everywhere possible”.

-AAP