An international human rights group says there is strong evidence that Kenya's anti-terrorism police unit has carried out a series of extrajudicial killings and enforced disappearances.

A Human Rights Watch report said on Monday that research conducted between November and June documented at least 10 cases of unlawful killings and 10 cases of enforced disappearances carried out by the unit.

At least 11 cases of mistreatment and harassment of suspects were also documented.