Geneva — WikiLeaks founder Julian Assange has suffered “psychological torture” from a defamation campaign against him by the media, judges and senior political figures, a UN human rights investigator said on Friday.

Nils Melzer, the UN special rapporteur on torture who visited Assange in a high-security London prison on May 9, voiced concern at fresh US criminal charges laid against Assange and reiterated a call for him not to be extradited...