The European Union banned all senior Uzbek officials from entering its member states in protest at the "indiscriminate and disproportionate" use of force by Uzbek authorities in a clash with protestors in the eastern city of Andijon in May.
Almatov has been granted permission to have a life-saving operation in Germany despite the EU ban.
A spokeswoman for Federal Prosecutor Kay Nehm said German prosecutors were investigating the complaints brought by New York-based Human Rights Watch and London-based Amnesty International, as well as by the United Nations’ special rapporteur on torture, Manfred Nowak.
Uzbek officials say 187 people were killed in Andijon following an alleged attempt by Islamist insurgents to take over city. But witnesses and human rights groups put the death toll substantially higher and say the Uzbek troops opened fire on unarmed protesters.