LONDON: British Prime Minister Theresa May has ordered a public inquiry into how contaminated blood was used to treat thousands in the 1970s and '80s, killing 2,400 people, according to officials. The announcement came after leaders of six political parties signed a letter calling for a probe into the scandal, in which hundreds of hemophilia patients reportedly died after being infected with HIV and hepatitis C through blood treatments. The letter said a new investigation should look into allegations of a cover-up. Labour lawmaker Diana Johnson called it "the worst treatment disaster in the history of the National Health Service" and said officials had failed to consider evidence of criminal activity. Downing Street said today the probe will aim to "establish the cause of this appalling injustice."