Canada and nearly two dozen mainly European countries voiced concern on Monday at the UN over alleged torture, unlawful detentions and unfair trials of critics, including women activists and journalists, in Saudi Arabia.

It was the second joint statement criticizing the kingdom read out at the UN Human Rights Council in Geneva in six months, following the first censure of Saudi Arabia at the forum in March.

The statement Monday urged Saudi authorities to establish the truth about the killing of journalist Jamal Khashoggi at the Istanbul Consulate last October and ensure the perpetrators are held to account.

Fifteen European Union members, including Britain and Germany, were among the signatories, as well as Canada, New Zealand and Peru, diplomats said.

There was no immediate response by the Saudi delegation, which is among the council's 47 member states but which has an empty seat. The Saudi ambassador left the room about an hour before to host his country's national day reception.

The kingdom has regularly denied allegations of torture and unfair detention.

The joint statement acknowledged Saudi reforms, including the announcement last month that restrictions on the rights of women to travel will be lifted, but said deep concerns remained.

"However, we remain deeply concerned at the human rights situation in Saudi Arabia. Civil society actors in Saudi Arabia still face persecution and intimidation," Australia's ambassador Sally Mansfield said, reading out the statement.

"We are concerned at reports of torture, arbitrary detention, enforced disappearances, unfair trials and harassment of individuals engaged in promoting and defending human rights, their families and colleagues," she said.

Loujain al-Hathloul, a former University of British Columbia student, is among a number of women activists who have been detained in Saudi Arabia for over a year. Rights groups say she and others have been held in solitary confinement for months and subjected to abuse.

Lina al-Hathloul urged the panel on Monday to call for the unconditional release of her sister and to hold those who've allegedly tortured the women to account. Rights groups working on behalf of Loujain Hathloul's release allege Saud al-Qahtani, a senior adviser to Crown Prince Mohammed bin Salman, has been a party to the inhumane treatment.

"They labelled her a traitor, tortured her and attempted to trade her freedom in exchange for her publicly denying the torture," she said.

Agnes Callamard, the UN expert on extrajudicial executions worldwide, said in a report last June that bin Salman and other senior officials should be investigated over Khashoggi's murder given what she called credible evidence against them.

In Riyadh, a minister rejected the report at the time as having nothing new and containing "baseless allegations." The Saudi public prosecutor has indicted 11 suspects, including five who could face the death penalty, for the crime.