A UN expert has concluded that Saudi Arabia undermined Turkey’s efforts to investigate the death of journalist Jamal Khashoggi, which she described as a “brutal and premeditated killing” planned and carried out by Saudi officials.

Agnes Callamard – the UN special rapporteur on extrajudicial, summary or arbitrary executions – made her assessment on Thursday after visiting Turkey.

She plans to present a final report to the UN Human Rights Council in June.

Mr Khashoggi, a Washington Post columnist who wrote critically about Saudi Crown Prince Mohammed bin Salman, was killed inside the Saudi Consulate in Istanbul on October 2.

Ms Callamard said in a statement that “woefully inadequate time and access was granted to Turkish investigators to conduct a professional and effective crime-scene examination and search required by international standards for investigation”.