A group of British lawmakers and international lawyers have asked Saudi authorities to visit eight detained female activists following reports that they have been tortured and sexually harassed, The Guardian reported on Wednesday.

The cross-party group said they want to document the conditions of the activists following the allegations that they have been subjected to abuse while in detention.

"The all-party panel includes the Conservative former chair of the foreign affairs select committee Crispin Blunt, the Liberal Democrat MP Layla Moran, and Paul Williams, a Labour member of the health and social care select committee," the report said.

Earlier this month, Human Rights Watch urged Riyadh to allow independent observers access to the detained women's rights activists.

The kingdom has denied as "false" and "unfounded" reports published by HRW and Amnesty International that some of the women activists had been tortured and sexually harassed in detention.

The move comes as Saudi Arabia faces intense global criticism over the killing of insider-turned-critic Jamal Khashoggi in its Istanbul consulate on October 2, which tipped the kingdom into one of its worst crises.

Saudi Arabia arrested over a dozen activists in May just before the historic lifting of a decades-long ban on female motorists the following month.

After their arrest, state-backed newspapers published front-page pictures of the jailed activists, calling them "traitors".

The detained activists include Aziza al-Yousef, a retired professor at Riyadh's King Saud University, and Loujain al-Hathloul - who was held in 2014 for more than 70 days for attempting to drive from neighbouring United Arab Emirates to Saudi Arabia.

Many of the activists are being held without charge or legal representation, campaigners say.

The arrests were seen as a calculated move by powerful Crown Prince Mohammed bin Salman to placate clerics incensed by his modernisation drive, as well as to send a clear signal to activists that he alone is the arbiter of change.