Channel 4 has launched an investigation after two women alleged that they were raped by partners they met on hit reality series Married at First Sight UK (MAFS).

The allegations, which are set to air as part of a BBC Panorama documentary on Monday evening, also include a third woman, who claimed she experienced a non-consensual sex act. The three men accused of wrongdoing denied the accusations, while Channel 4 and producer CPL Productions said welfare protocols were followed.

According to a just-published BBC News article, one of the women alleged that her onscreen husband raped her and threatened her with an acid attack. The second woman said she told Channel 4 and CPL that she was raped by her onscreen husband and her episode still aired.

Channel 4 told BBC News the allegations were “wholly uncorroborated and disputed,” but the network has also launched an investigation and removed all MAFS episodes from its streaming service. Lawyers for CPL Productions told BBC News they disputed elements of the claims.

Channel 4 CEO Priya Dogra said it commissioned an external review in April. This came after Channel 4 was “presented with serious allegations of wrongdoing against a small number of past contributors” and was initially asked to probe internally, which found that “when concerns related to contributor 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 network added.

The external review has two elements, Channel 4 said. One, being overseen by law firm Clyde & Co, is “examining the welfare protocols in place on this programme at the time claims were raised, as well as the handling by Channel 4 and CPL of those claims.” The other is being led by former BBC One Controller Lorraine Heggessey, who is probing whether “any changes should be made to current protocols for MAFS UK to further strengthen contributor welfare.”

Channel 4 said it expects the review to report in the coming months and will share a summary of findings and recommendations “at the appropriate time.” It is at least the third external review it has launched this decade, following one into the suicide of true crime producer John Balson and another into the behavior of Escape to the Chateau hosts Dick and Angel Strawbridge. The Balson review found that Channel 4 had acted “reasonably and appropriately” with its duty of care before the producer took his own life. Channel 4 cut ties with the Strawbridges after the review.

While noting “it would be wholly inappropriate for me to comment on what are very serious allegations made against some MAFS UK contributors,” Dogra said she believes Channel 4 “acted quickly, appropriately, sensitively and with wellbeing front and centre” when “concerns about contributor welfare were raised.”

“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,” she added. “We take these issues very seriously and are committed to ensuring that we continue to lead the industry in our duty of care for contributors.”

Married at First Sight UK is one of Channel 4’s biggest hits and has been airing for more than a decade. As of now, all episodes have been removed from Channel 4’s VoD player. The show airs in multiple territories around the world, including in the U.S. on Peacock.

CPL Productions declined to comment beyond pointing to Channel 4’s statement.