A Turkish court decided on Thursday to halt the trial of Saudi suspects over the killing of journalist Jamal Khashoggi and transfer it to Saudi Arabia, a ruling that drew condemnation from rights groups and comes as Ankara mends ties with Riyadh.

The decision was expected after the prosecutor called last week for the trial in absentia of 26 Saudi suspects to be transferred from Istanbul to Riyadh. The justice minister later endorsed the request.

Khashoggi's killing at the Saudi consulate in Istanbul four years ago raised a global outcry and put pressure on Saudi Arabia's de facto ruler Crown Prince Mohammed bin Salman.

Turkish officials said they believe Khashoggi, a prominent critic of the crown prince, was killed and his body dismembered in an operation which President Tayyip Erdogan said had been ordered at the "highest levels" of the Saudi government.

The judge's ruling marks a turnaround in the trial that began in 2020.

"Making the decision to halt (the trial) is against the law... because the acquittal ruling about the defendants in Saudi Arabia has been finalised," said Gokmen Baspinar, a lawyer representing Hatice Cengiz, the murdered journalist's fiancée.

"The fact that the trial is being transferred to a country where there is no justice is an example of irresponsibility against the Turkish people," he said.

The Saudi government media office did not immediately respond to requests for comment.

A US intelligence report released a year ago said Prince Mohammed had approved the operation to kill or capture Khashoggi, but the Saudi government denied any involvement by the crown prince and rejected the report's findings.

The killing and subsequent accusations strained ties between the two Sunni Muslim regional powers and led to an unofficial Saudi boycott of Turkish goods, which cut Ankara's exports to Riyadh by 90%.

But with Turkey keen for investment to boost its economy, Ankara has sought over the last year to heal the rift with Riyadh.

Erdogan said last month Turkey was continuing a "positive dialogue" with Saudi Arabia and wants to take concrete steps to improve ties. The respective foreign ministers held talks two weeks ago and agreed to improve ties, Ankara said.

Ahead of the ruling, Human Rights Watch had warned that transferring of the trial to Riyadh would block justice.

It "would end any possibility of justice for (Khashoggi), and would reinforce Saudi authorities' apparent belief that they can get away with murder", said Michael Page, deputy Middle East director at Human Rights Watch.