The US-allied United Arab Emirates (UAE) is a key member of the Saudi-led coalition against Houthi rebels in Yemen, who have the backing of Iran. The UAE has developed militia forces across southern Yemen.

In its report  "Disappearances and torture in southern Yemen detention facilities must be investigated as war crimes," which was published Thursday, Amnesty claimed the existence of "a network of secret prisons" had first been exposed a year ago.

As violations continued unchecked, the rights group said there were "enforced disappearances and torture and other ill-treatment amounting to war crimes."

Tirana Hassan, crisis response director at Amnesty International, said the families of detainees found themselves in "an endless nightmare where their loved ones have been forcibly disappeared by UAE-backed forces."

Read more: Germany sells arms to UAE despite Yemen conflict

UAE calls for independent investigation

In response to the report, the UAE issued a statement on Thursday urging an independent investigation into the allegations: "The UAE has urged the Yemeni government to conduct an independent investigation into the matter and continues to follow up with the Yemeni government on this front."

On Monday, Yemen's interior minister in the southern-based government, Ahmed al-Maysari, demanded the UAE shut down or hand over control of secret prisons.

Some 80 detainees have been freed from the prisons in recent weeks.

Previously, the UAE state minister for foreign affairs, Anwar Gargash, dismissed as "fake news" the prison reports, or suggestions that the UAE has a base on the Yemeni island of Socotra.

Security Belt and Elite Forces

The Abu Dhabi government claimed the reports were designed to undermine the Arab coalition: "The UAE believes that these reports are politically motivated to undermine its efforts as part of the Arab coalition to support the Yemeni government."

The UAE intervened in the Yemeni conflict in 2015 and has developed the Security Belt and Elite Forces, a militia based in southern Yemen which is officially under the control of Yemen's interior ministry.

According to The Associated Press, the Security Belt is responsible for the Beir Ahmed prison in Aden, where there have been reports of extensive human rights violations.

jm/rc (Reuters, AP)

Each evening at 1830 UTC, DW's editors send out a selection of the day's hard news and quality feature journalism. You can sign up to receive it directly here.