The family of British academic Jason Arday, who was found dead at a South London address on Friday night amid a high-profile plagiarism storm, have denounced what they called years of "sustained abuse".

In an overnight statement following Arday's death, his family said he had been "subjected to a campaign of sustained abuse for more than three years since he accepted the role of professor at Cambridge University".

Arday had himself alleged a "racially motivated" campaign against him.

Speaking to reporters on Saturday, British Prime Minister Andy Burnham said "it's a tragedy on so many levels, but particularly just for everybody who knew Jason, his family obviously, his friends."

Burnham also said it was not the time for "any rushing to judgement", and that now is "a moment for reflection... reflecting on how things came to this."