The members of the Security Council reaffirmed the need to combat by all means, in accordance with the Charter of the United Nations and all obligations under international law, in particular international human rights, refugee and humanitarian law, threats to international peace and security caused by terrorist acts.

UN: Security Council

International treaties constitute a major source of international law and are critical to establishing the respective rights and obligations of states in relation to many political, economic, military, environmental and other matters.

BBC: Scotland politics

But they say the abuse was systemic and only a fully independent inquiry will satisfy the UK's international human rights obligations.

BBC: Iraqis claim British troops 'acted with brutality'

In a joint statement, the groups said Egypt's "international obligations require it to respect the rights of detainees, which include to be informed promptly and in detail of the charges against them".

BBC: Rights groups press Egypt over arrests