An advocacy group said Tuesday that the U.S. Department of Homeland Security's internal watchdog fielded more than 1,000 complaints of sexual assault or sexual abuse from people in custody in a little more than two years.

Community Initiatives for Visiting Immigrants in Confinement is the latest group in recent years to document allegations of abuse at immigration detention centers, based on information obtained from public records requests. It comes as President Donald Trump seeks to expand detention capacity in a drive to deport more people.

The numbers obtained by the group don't provide details on individual cases or a full accounting of how the complaints were addressed, but they suggest complaints are common.

The Homeland Security inspector general's office disclosed that it received 1,016 complaints from detainees reporting sexual abuse or assault from May 2014 to July 2016. More than 90 percent involved Immigration and Customs Enforcement, an agency within Homeland Security that has more than 30,000 beds at detention facilities nationwide.

The inspector general received more than 33,000 allegations of a broader range of abuses from January 2010 to July 2016, including 702 for coerced sexual contact, 714 for physical or sexual abuse and 589 for sexual harassment, according to the group. The group's analysis showed the inspector general investigated 247, or less than 1 percent. But it was unclear how many others were taken up by agencies in the department, such as Immigration and Customs and Enforcement or Customs and Border Protection.

The group cited the numbers in a complaint to Homeland Security Secretary John Kelly that urges changes in how allegations are handled. Gillian Christensen, a Homeland Security spokeswoman, said the department would review the complaint "to determine if further action or recommendations are warranted."

Christensen noted the allegations represent a small number of the more than 2 million admissions to Immigration and Customs Enforcement detention facilities in the six-year period covered in the report. She said the agency has a "zero tolerance policy" and listed steps it has taken to address sexual abuse of detainees, including a directive to employees on prevention and intervention.

"While ICE's goal is to prevent all sexual abuse among its custody population, given the volume of individuals who annually pass through its detention system, the agency believes the overall incidence of such activity is very low," she said.

The inspector general's office usually focuses on allegations of employee misconduct and often refers complaints of detainee abuse to Immigration and Customs Enforcement's Office of Professional Responsibility to follow up, Christensen said.

Community Initiatives for Visiting Immigrants in Confinement said it independently documented 27 alleged instances of sexual abuse. Most haven't filed grievances because they fear retaliation.

Douglas Menjivar was allegedly raped by another detainee in the presence of four witnesses at the Joe Corley Detention Center in Conroe, Texas, in September 2013. The group says an official told him that he was stupid to let it happen and that the facility didn't document Menjivar's claim or provide medical or psychological care. Menjivar reported the incident to a doctor in November 2014, and after being interviewed twice, authorities told him that his allegations were unsubstantiated.

The group also published figures, obtained from a records request by Human Rights Watch, that show private companies contracted by Immigration and Customs Enforcement had the most hotline complaints of sexual and physical assault from Oct. 1, 2012 to March 14, 2016, as opposed to centers managed by the agency. Detention centers managed by The Geo Group Inc. occupied first, third and fourth slots with facilities in Jena, Louisiana; Adelanto, California; and Tacoma, Washington. CCA Inc. facilities in Houston and San Diego occupied the second and fifth slots.