The Married at First Sight franchise has been left reeling by allegations of rape from a group of ex-contestants in a new BBC Panorama investigation.

On Monday, it came to light that two women on Channel 4‘s MAFS UK — where singletons are matched, by experts, with a stranger and meet for the first time at a mock wedding — claimed they had been raped during filming of the show.

The first said her husband had raped her and later threatened her with an acid attack, while a second woman told Channel 4 and production company CPL before broadcast about being allegedly raped by her husband. Her episodes, according to the BBC program, were still aired. A third woman, Shona Manderson, the only one to have revealed her identity, accused her onscreen husband of a non-consensual sex act. The men involved deny the claims, challenging the details of each woman’s account.

The former participants who have come forward say Channel 4 did not do enough to protect them. The BBC reported that Channel 4 was aware of some allegations before broadcast, but had previously told Panorama that all of the claims were “wholly uncorroborated and disputed.”

In the wake of the news, Channel 4 has removed all episodes of the program from its streaming and linear services, as well as the MAFS UK social media accounts. Holiday company Tui told the BBC that it was pausing sponsorship of the show.

MAFS is Love Island-esque in its global popularity, with localized versions in over 35 countries. The U.K. series has been running for 10 seasons now and often boasts viewership of over three million, making it one of Britain’s most prized reality shows. The latest season has already been filmed is expected to air this year.

When approached for comment by The Hollywood Reporter, a representative for Channel 4 referred to an announcement, made this week, that it commissioned an external review into contributor welfare on the show in April.

“MAFS U.K. is produced under some of the most comprehensive and robust welfare protocols in the industry,” said the channel. “These include the most thorough background checks available, a Code of Conduct which clearly sets out behavioural standards, daily contributor check-ins with a specialist welfare team and access to additional support before, during and after filming. The physical and psychological well-being of all contributors is of paramount importance throughout the process. All duty of care processes are regularly reviewed and, where appropriate, strengthened.”

The letter continued that last month, Channel 4 was presented with “serious allegations of wrongdoing against a small number of past contributors, allegations that we understand those contributors have denied.” They added that when concerns related to contestant welfare were raised through existing welfare and production protocols, “prompt and appropriate action was taken, based on the information available at the time. Channel 4 strongly refutes any claim to the contrary.”

The external review, conducted by law firm Clyde & Co, is now underway. It has two elements: examining the welfare protocols in place on MAFS UK at the time the claims were raised, and if any changes should be made to further strengthen the current protocols.

“I want to express my sympathy to contributors who have clearly been distressed after taking part in Married at First Sight UK,” said Channel 4 chief executive Priya Dogra. “The well-being of our contributors is always of paramount importance. 

“It would be wholly inappropriate for me to comment on what are very serious allegations made against some MAFS UK contributors,” she continued. “Those allegations — which I understand are disputed by the contributors accused — are not something that Channel 4 is in a position to adjudicate on. We are also mindful of our ongoing duty of care to all contributors, and the need to preserve the anonymity and privacy of all involved.”

Dogra believes that Channel 4 “acted quickly, appropriately, sensitively and with wellbeing front and centre,” when the allegations were first made.

“Nevertheless, because we aspire to the highest standards of contributor welfare, I felt strongly as Channel 4’s new CEO that it was right that we look again at how we handled issues raised at the time and ask whether changes should be made to further strengthen contributor welfare… That’s why last month I commissioned an external review of contributor welfare on MAFS UK. That review will report to me in the coming months,” she said.