(afp) -- The UAE is a key member of a Saudi-led military coalition that entered Yemen's conflict in 2015 to battle on the government's side against Huthis .
HRW said UAE officials appeared to have "moved high-profile detainees outside the country" including to a base in Eritrea.
The rights group said it had documented 49 cases, including those of four children, who had been "arbitrarily detained or forcibly disappeared" -- at least 38 of them by UAE-backed forces.
The New York-based group said the UAE also runs detention facilities in southern provinces home to Al-Qaeda in the Arabian Peninsula and a local affiliate of the ISIS group.
Children are among those detained in the centres, it said.
The World Health Organization estimates more than 8,000 people have been killed in two years of conflict in Yemen, which also faces a deadly cholera outbreak and the threat of famine.
The United Nations and HRW have said air strikes by the Saudi-led alliance have killed many civilians and may amount to war crimes.