Investigations into the devastating twin bomb attack that killed at least 16 and injured over 100 in Hyderabad on Thursday must be "prompt, effective and transparent", the Amnesty said
Many of those arrested in the Mecca mosque blast had been detained without charge and subjected to torture. No action was taken against those responsible for the torture, the Amnesty said, adding that this must not happen again.
"Shoddy investigations and unlawful police practices can violate the fair trial rights of suspects, and also the victims' right to justice," said G Ananthapadmanabhan, the head of Amnesty's India operations said.
The authorities must bring those responsible for the attacks to justice in fair trials in line with international rights standards, without recourse to the death penalty, the organisation said.