Crown Prince Mohammed bin Salman of Saudi Arabia authorised a secret campaign to silence dissenters – which included the surveillance, kidnapping, detention and torture of Saudi citizens – more than a year before the killing of Jamal Khashoggi, according to US officials who have read classified intelligence reports about the campaign.

At least some of the clandestine missions were carried out by members of the same team that killed and dismembered Khashoggi in Istanbul in October, suggesting that his killing was a particularly egregious part of a wider campaign to silence Saudi dissidents, according to the officials and associates of some of the Saudi victims.

Members of the team that killed Khashoggi, which US officials called the Saudi Rapid Intervention Group, were involved in at least a dozen operations starting in 2017, the officials said.

Some of the operations involved forcibly repatriating Saudis from other Arab countries and detaining and abusing prisoners in palaces belonging to the crown prince and his father, King Salman, the officials and associates said.

One of the Saudis detained by the group, a university lecturer in linguistics who wrote a blog about women in Saudi Arabia, tried to kill herself last year after being subjected to psychological torture, according to US intelligence reports and others briefed on her situation.

Jamal Khashoggi death: key figures Show all 7 1 /7 Jamal Khashoggi death: key figures Jamal Khashoggi death: key figures Jamal Khashoggi Washington Post journalist who was critical of the Saudi regime and the young Crown Prince Mohammed bin Salman, he was murdered on 2 October in the Saudi Arabian consulate in Istanbul AFP Jamal Khashoggi death: key figures Saudi Crown Prince Mohammed bin Salman Heir to the Saudi throne, Mohammed bin Salman has been implicated in the murder, with US officials claiming that he must have known of the plot AFP/Getty Jamal Khashoggi death: key figures 15 man hit squad Turkish police suspect these 15 men of being involved in the murder of Jamal Khashoggi, issued 10 October, 8 days after the journalist disappeared EPA Jamal Khashoggi death: key figures Saud al-Qahtani Aide to Crown Prince Mohammed bin Salman, Saud al-Qahtani is claimed to have ordered Khashoggi's murder Saud Al-Qahtani/Twitter Jamal Khashoggi death: key figures Maher Abdulaziz Mutreb A former diplomat who often travelled with the Crown Prince, Mutreb was initially claimed to be the leader of the hit squad and is pictured here entering the Saudi consulate on the day of the murder AP Jamal Khashoggi death: key figures Mustafa al-Madani First implicated in the 15 CCTV photos released by the Turkish police, al-Madani was later found to have been used as a body double for Khashoggi, leaving the Saudi consulate dressed in his clothes on the day the journalist was killed CNN Jamal Khashoggi death: key figures Salah bin Jamal Khashoggi (L) Son of the murdered journalist met with Crown Prince Mohammed bin Salman on 23 October EPA

The rapid intervention team had been so busy that last June its leader asked a top adviser to Crown Prince Mohammed whether the crown prince would give the team bonuses for Eid al-Fitr, the holiday marking the end of Ramadan, according to US officials familiar with the intelligence reports.

Details about the operations come from US officials who have read classified intelligence assessments about the Saudi campaign, as well as from Saudis with direct knowledge of some of the operations. They spoke on the condition of anonymity for fear of repercussions from disclosing classified information or, in the case of the Saudis, from angering the Saudi government.

A spokesperson for the Saudi Embassy in Washington said the kingdom “takes any allegations of ill treatment of defendants awaiting trial or prisoners serving their sentences very seriously.”

Saudi laws prohibit torture and hold accountable those involved in such abuses of power, the spokesperson said, and judges cannot accept confessions obtained under duress. The kingdom’s public prosecutor and the Saudi Human Rights Commission are investigating “recent allegations,” he said.

The Saudi government insists that the killing of Khashoggi – a dissident journalist living in the United States who wrote for The Washington Post – was not an assassination ordered from Riyadh. The decision to kill him was made by the team on the spot, government officials say, and those responsible are being prosecuted. Turkey and US intelligence agencies say the killing was premeditated.

The kingdom says 11 Saudis are facing criminal charges for the killing and that prosecutors are seeking the death penalty for five of them, but officials have not publicly identified the accused.

After the killing of Khashoggi, Saudi officials acknowledged that the Saudi intelligence service had a standing order to bring dissidents home. What they did not acknowledge was that a specific team had been built to do it.

Saudi officials declined to confirm or deny that such a team existed, or answer questions about its work.

Saudi Arabia has a history of going after dissidents and other Saudi citizens abroad, but the crackdown escalated sharply after Mohammed bin Salman was elevated to crown prince in 2017, a period when he was moving quickly to consolidate power. He pushed aside Prince Mohammed bin Nayef, who oversaw the security services, giving the young prince sway over the intelligence agencies.

Since then, Saudi security forces have detained dozens of clerics, intellectuals and activists who were perceived to pose a threat, as well as people who had posted critical or sarcastic comments about the government on Twitter.

“We’ve never seen it on a scale like this,” said Bruce Riedel, a former CIA analyst now with the Brookings Institution. “A dissident like Jamal Khashoggi in the past wouldn’t have been considered worth the effort.”

The Rapid Intervention Group was authorised by Crown Prince Mohammed and overseen by Saud al-Qahtani, a top aide whose official job was media czar at the royal court, US officials said. His deputy, Maher Abdulaziz Mutreb, an intelligence officer who has travelled abroad with the crown prince, led the team in the field.

Another operative on the team was Thaar Ghaleb al-Harbi, a member of the royal guard who was promoted in 2017 for valour during an attack on a palace of Crown Prince Mohammed’s.

Mr Mutreb and Mr al-Harbi are on trial in Riyadh for charges connected to Khashoggi’s death, a Saudi official said, while Mr al-Qahtani is under house arrest, has been banned from travel and is under investigation, making it unclear whether the team is still operating.

US intelligence reports did not specify how involved Crown Prince Mohammed was with the group’s work, but said that the operatives saw Mr al-Qahtani as a “conduit” to the prince.

Republican senator Lindsey Graham says Saudi Crown Prince complicit in murder of Jamal Khashoggi 'to the highest level possible'

When Crown Prince Mohammed locked hundreds of princes, businessmen and former officials in the Riyadh Ritz-Carlton in 2017 on accusations of corruption, Mr al-Qahtani and Mr Mutreb worked in the hotel, helping pressure detainees to sign over assets, according to associates of detainees who saw them.

Many of those detained at the Ritz were subject to physical abuse, and one died in custody, according to witnesses. It is not known whether members of the rapid intervention team were involved in the abuse. The Saudi government has denied that any physical abuse took place there.

But it was only after Khashoggi’s killing that the extent of the team’s work began to emerge. Mr Mutreb and Mr al-Harbi were both in the consulate when Khashoggi was killed, according to Turkish officials. US intelligence about the team’s previous operations informed the assessment by the CIA in November that Crown Prince Mohammed had ordered Khashoggi’s killing, US officials said.

The CIA declined to comment.

US intelligence agencies do not appear to have conclusive proof that Crown Prince Mohammed ordered the killing, but they have pieced together a pattern of similar operations carried out by Saudi operatives under the prince’s authority.

The agencies continue to gather evidence about Crown Prince Mohammed’s role in the operations, and in December the National Security Agency produced a report saying that in 2017, the prince told a top aide that he would use “a bullet” on Khashoggi if he did not return to the kingdom and end his criticism of the government.

Intelligence analysts concluded Crown Prince Mohammed may have not spoken literally – that he was not ordering Khashoggi to be shot – but he intended to silence the journalist by killing him if the circumstances required it.

The Rapid Intervention Group also appears to have been involved in the detention and abuse of about a dozen women’s rights activists, who were detained last spring and summer. The activists, who had campaigned for lifting the kingdom’s ban on driving by women, included several well-known figures: Loujain al-Hathloul, who had been jailed for trying to drive her car into the kingdom from the United Arab Emirates; Aziza al-Yousef, a retired computer science professor; and Eman al-Nafjan, the linguistics lecturer.

At first, the women were not held in a prison, but were detained informally in what appeared to be an unused palace in the Red Sea port city of Jiddah, according to Ms al-Hathloul’s sister, Alia. Each woman was locked in a small room, and the windows were covered. Some of the women were frequently taken downstairs for interrogation, which included beatings, electric shocks, waterboarding and threats of rape and murder.

In an op-ed article for The New York Times, Alia al-Hathloul wrote that Mr al-Qahtani was “present several times” when her sister was tortured, and that he threatened to kill her and throw her body in the sewer.

The treatment was so harsh that Ms al-Nafjan tried to commit suicide, according to a US intelligence assessment.

The women were later moved to the Dhahban Prison in Jeddah, where the physical abuse stopped and their relatives were allowed to visit, Ms al-Hathloul said.

Their trial opened in Riyadh on Wednesday, but journalists and diplomats were not permitted to attend, and the government did not announce the charges against them.

The Saudi official said Ms al-Hathloul, Ms al-Yousef and Ms al-Nafjan were being tried “in connection with activities that threatened the kingdom’s national security.”