White House staff were warned not to use insider information to place bets on prediction markets in March. The email, sent the day after US President Donald Trump paused his threat against Iran, followed reports that government officials might be using non-public info.

The Wall Street Journal first reported the email, while White House spokesman Davis Ingle stated that all federal employees are subject to ethics guidelines prohibiting insider information for financial gain. Congressman Ritchie Torres called for an investigation into suspicious trades on prediction markets this week, as they have become increasingly popular and controversial.

Prediction market bets can be placed on anything, from sports results to economic policies. But the industry has faced scrutiny over conflicts in particular, with some arguing that it should be completely banned related to war or military action.

Senator Andy Kim said: 'Corruption and exploitation are thriving right now within the gaps and loopholes of prediction markets.' Will such concerns lead to stricter regulation?