One Direction and 5 Seconds of Summer fans were left frustrated on Sunday (April 3) after they lost out in a fan prize at this year's iHeartRadio Music Awards.

Justin Bieber's supporters won the Best Fan Army gong at the event in California.

However, fans of acts like One Direction, 5 Seconds of Summer and Fifth Harmony have been speaking out against the awards, claiming that the vote may have been rigged.

The term '#iFakeAwards' started trending on Twitter post-show as fans of other artists highlighted that only minutes before the public vote closed, Bieber wasn't even in the top three.

A One Direction fan wrote on Twitter: "*5 mins before the voting closes* Directioners: 1st 5sos Fam: 2nd Harmonizers: 3rd *Beliebers wins*."

Another fan quipped: "New single from One Direction, 5sos & 5h called "Steal My Award" currently #1 in more than 96 countries #iFakeAwards."

Bieber, who attended the event, issued a last minute plea for fans to vote, saying:

"Got the message. RT this. #BestFanArmy #Beliebers and #iHeartAwards."

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Watch Justin Bieber perform live below: