Human Rights Watch (HRW), Freedom Now and MENA rights are among some of the NGOs due to present evidence into the enforced disappearance and detention of former Saudi Crown Prince Muhammed Bin Nayef and Prince Ahmed Bin Abdul.
The live evidence session which will be presented to a fact-finding panel consisting of British parliamentarians and international lawyers, is scheduled to take place on 17 November.
This comes after human rights activists made a renewed plea for world leaders not to attend the G20 summit in Saudi Arabia planned for later this month, due to such dire human rights situation in the country.
Both Princes have reportedly been denied access to legal advice, medical care and communication with their family members after being suddenly detained and disappeared in March.
READ: US lawmakers urge boycott of Saudi G20 summit
Bin Nayef is being held along with two other senior royals in an undisclosed location. The former crown prince was ousted from the post in what many have said was a "palace coup" carried out by current Crown Prince Mohammed Bin Salman which led to Bin Nayef being held under house arrest.
The panel will seek to establish the detention conditions and treatment of the princes and other key political figures detained in the region.
Saudi authorities arrested a number of human rights activists, including Loujain Al-Hathloul, Samar Badawi, Nassima Al-Sada, Nouf Abdel Aziz and Maya Al-Zahrani, on 15 May 2018, for allegedly harming the kingdom's security.
However, human rights reports said the activists had been arrested for defending women's rights.
The panel's chairman, the UK's Conservative MP Crispin Blunt said: "We are honoured that a number of well-established and credible human rights organisations who have been investigating the situation in Saudi Arabia for many years are attending the parliamentary panel's live session to provide evidence to the Panel."
The Saudi government has also been invited to participate in the live evidence session through the ambassador to London, however the panel are yet to receive a response.
READ: Saudi Embassy contradicts the ambassador and denies clemency for female activists
Blunt added: "Their evidence will play a crucial role in shaping the Panel's conclusions and recommendations, due to be published in our report later this year. With the G20 summit fast approaching, the eyes of the international community are firmly on Saudi Arabia. This session offers an opportunity to hear direct evidence from experts regarding the detention conditions experienced by many high profile and prominent detainees in the region."
The kingdom is due to host a virtual leaders' summit on 21-22 November, as it currently holds the presidency of the G20 group.