Human Rights Watch, headquartered in New York, said in a statement it has evidence of "at least 10 cases of killings, 10 cases of enforced disappearances, and 11 cases of mistreatment or harassment of terrorism suspects" since 2011.
The unit, funded by the United States and United Kingdom, was organized in 2003, after al-Qaida militants bombed U.S. embassies in Kenya and Tanzania on the same day in 1998.
A report issued by Human Rights Watch stated:
"Suspects were shot dead in public places, abducted from vehicles and courtrooms, beaten badly during arrest, detained in isolated blocks, and denied contact with their families or access to lawyers ... Donors need to carry out their own investigations of these abuses and suspend their assistance to abusive forces, or risk being complicit in Kenya's culture of impunity."
The anti-terrorism unit is currently involved in a conflict with al-Shabaab, a group linked to al-Qaida and responsible for a 2013 assault on a Nairobi, Kenya, shopping mall, which killed 67 people. That attack and more recent ones in Kenya were in response to Kenya's involvement in supporting the government of neighboring Somalia, al-Shabaab has said.