Bandar bin Mohammed al-Aiban said those on trial for what he described both as an "unfortunate accident" and a "heinous crime" had attended three hearings so far with their lawyers present - but he gave no names or other details.

Khashoggi, a Washington Post columnist and critic of Saudi Crown Prince Mohammed bin Salman, was killed in the Saudi consulate in Istanbul on Oct. 2, provoking an international outcry.

Three dozen Western countries, including all 28 European Union members, called on the kingdom last week to cooperate with a U.N.-led investigation.

But Aiban told the U.N. Human Rights Council that Saudi Arabia would not accept what he termed as foreign interference in its domestic affairs and judicial system.

"Justice in the kingdom of Saudi Arabia operates pursuant to international law and it does so in all transparency," Aiban told the Geneva forum during a review of Saudi Arabia's rights record.

Read: Turkey Planning International Investigation into Khashoggi Case

“We are indeed horrified by what has happened pursuant to this unfortunate accident and we have taken those measures required for us to resolve this heinous crime,” added Aiban, who headed the official Saudi delegation at the hearing.

Turkey, which has repeatedly pressed Riyadh to reveal more details of the killing, said Saudi authorities should disclose the names of defendants and the charges they face if it wanted to avoid questions over the "sincerity of judicial proceedings in the kingdom".

It also criticized Aiban's rejection of any foreign investigation. "We find it difficult to understand why an official working in the area of human rights would possibly be unsettled by efforts to shed light on all aspects of the Khashoggi murder," the Turkish presidency said.

Riyadh has rejected accusations by the CIA and some Western countries that the crown prince ordered the killing.

After making numerous contradictory statements, it said Khashoggi was been killed after negotiations to persuade him to return to Saudi Arabia failed - and later that 11 Saudis had been indicted and referred for trial over the case, without identifying them.

The public prosecutor is seeking the death penalty for five of them.

The killing has severely strained ties between Turkey and Saudi Arabia, although Turkish President Tayyip Erdogan has good ties with the Saudi monarch, King Salman.

REUTERS