(CNN) Three women have accused Gambia's ex-president, Yahya Jammeh, of carrying out a series of rapes and sexual assaults while in power, according to Human Rights Watch and TRIAL International, a group that advocates for crime victims.

The organizations allege that Jammeh used his aides to pressure women to visit him in his private residence where he would sexually abuse them, according to a statement from Human Rights Watch Wednesday.

"Yahya Jammeh treated Gambian women like his personal property," Reed Brody, of Human Rights Watch, said in a statement. "Rape and sexual assault are crimes, and Jammeh is not above the law."

The accusations first came to light Tuesday in a New York Times interview with one of the former president's alleged victims.

Jammeh was Gambia's leader from 1994 to 2016; he took power in a military coup but suffered a surprise election defeat to Adama Barrow in December 2016.

He is currently living in exile in Equatorial Guinea.

Jammeh has not responded to efforts to reach him. However, Ousman Rambo Jatta, the Deputy leader of the Alliance for Patriotic Reorientation and Construction Party (APRC), the ruling party when Jammeh was president, said in a statement to CNN the allegations of rape had "no iota of truth."

CNN also spoke with the party's UK spokesman, who noted that Jammeh remains the party leader and that the party often speaks on his behalf. He said they have been in contact with Jammeh's team and the former president will not be making a comment on this matter.

Cash, gifts, promises

Human Rights Watch and TRIAL International said they had interviewed three women who recounted suffering rape and sexual assault at the hands of Jammeh, and a fourth woman who said the president's staff tried to trap her with him, but she was not assaulted.

Human Rights Watch said the women they interviewed alleged that the former president "forced or coerced young women into having sex with him. Some were put on the state payroll and worked at State House as so-called 'protocol girls,'" who were given cash and gifts, and promised scholarships and other privileges.

Witnesses, who were not named, also told Human Rights Watch investigators that "both consensual and non-consensual sex took place at the president's residences."

In his response to the allegations, Jatta, the APRC's Deputy leader said: "APRC is utterly disappointed to have been, once again, confronted with malicious allegations against its party leader and the ex-President of The Republic of The Gambia."

Jatta said the allegations hailed from "Western corporations that have been and will continue to lead smear campaigns to tarnish the good reputation of Gambia's legendary and visionary leader," adding that the party and the "Gambian people are tired of the steady stream of unfounded allegations that have been reported against our ex-President."

One of the president's alleged victims is speaking out publicly. HRW interviewed Fatou Jallow, who also spoke to the New York Times and the Guardian. She alleged that Jammeh raped her in June 2015, at what was billed as a religious event to mark the start of Ramadan, when she was 18. The other two alleged rape victims asked to remain anonymous, according to HRW.

CNN does not normally name rape victims, but Jallow has come forward in international media, telling the New York Times that it is important to tell her story publicly, despite fears of bringing shame to her family, because, "in the end the silence is as uncomfortable and more damaging than the consequences of speaking."

Rejected advances

Jallow, also known as Toufah, said she first came into contact with the then-president after she appeared in a beauty contest run by Gambia's Ministry of Education in 2014. She said she was eventually invited to visit him -- in his private residence -- to discuss the drama project she had submitted during the pageant.

He gave her gifts and installed running water at her family's home, Jallow told HRW interviewers. But Jammeh's attitude towards her changed after she rejected his advances, which included a marriage proposal, she said.

Jallow said that during a visit to the State House to mark Ramadan, she found herself alone with Jammeh.

"He told me, 'No woman has ever rejected me. And who do you think you are?'" she told HRW. "He said, 'No woman rejects me. You think you can get away with it?'"

She told interviewers that she screamed, and he slapped her, told her to shut up, and then injected her in her arm with a needle, before raping her.

She said she lost consciousness and when she came around some time later, the president made her get her out of the building.

As she was leaving, she said an aide told her: "He is the president, and we will do everything to protect him."

Gambia has set up a Truth, Reconciliation and Reparations Commission to investigate alleged abuses committed during Jammeh's 22 years in power. According to HRW, Jallow is expected to testify later this year.