A 23-year-old asylum seeker from El Salvador, who is currently being held at a Texas detention centre, is claiming she has been repeatedly sexually assaulted by a female guard for nearly six months.

The woman, who has been detained since June after attempting to cross the US-Mexico border in May, told The Independent she was scared to speak out for fear of retaliation at the Hutto Residential Centre in Taylor, Texas. She claimed the female guard would lead her to a recreation room in the dentition centre where she repeatedly groped her.

"In this place, we don't have rights, only duties," she said in a letter to Grassroots Leadership, an immigration advocacy group in Austin. "We are not criminals, we only want to protect our lives, we can't stand any more torture or threats."

The letter continued: "She looked for, or took advantage of every moment she could to touch my breasts or my legs, she knew where and when she did it, I don't remember dates because there are so many."

According to the Independent, the abuse finally stopped when the guard was moved after an anonymous tip to the facility's officials.

The detained woman said she has seen the guard since the anonymous tip and feared the guard was only moved to a different part of the facility. She decided to come forward with her claims after losing her asylum case last month.

"She was really scared that the guard would have some sort of influence over her case, and the guard made threats towards her saying that nobody would believe her if she said anything about it," Claudia Munoz, of Grassroots Leadership, told the Independent.

The woman was also concerned she would be transferred to another detention centre and would be forced to restart her case with a new judge.

Grassroots Leadership said the woman has met with a sexual abuse task force, which included representatives from the detention centre, officials from the Williams County Sheriff's Office and Immigration and Customs Enforcement (ICE). She previously met with investigators following the anonymous tip to officials.

It is unclear whether the task force will continue an investigation following the meeting, or if the guard will face punishment if a probe supports the allegations, the group said.