Justin Bieber has come under fire from parents of young fans who were left waiting for nearly two hours when the pop star took to the stage late at a concert in Iowa on Sunday night (07Jul13).

The Baby hitmaker delayed the start of his show at the Wells Fargo Arena in Des Moines and didn't take to the stage until gone 10pm (local time).

The delay meant the young children in the audience were kept waiting, and didn't leave the venue until nearly midnight.

Bieber's tardiness infuriated parents whose kids attended the gig, and one irate mother has now written an angry open letter to the star which has been published in local newspaper The Des Moines Register.

Jill Stuecker, from West Des Moines, warns the singer his bad behaviour will alienate his fans' parents - and they are the ones who actually buy his albums, concert tickets and merchandise.

She writes, "Dear Justin Bieber, I get it. You are young, rich and famous. I'm sure that 90 per cent of the time people are more than happy to accommodate your schedule, or lack thereof. Here's the deal, parents who have their kids at one of your concerts on a Sunday night are not among that 90 per cent... Your livelihood is primarily dependent upon a fan base of people who do not have their own incomes. Translation: You really shouldn't tick off mom and dad...

"I am beyond irritated that you started your concert so late... Based on the loud booing from the audience, and all of the post-concert chatter going on Monday, many others are, too..."

She goes on to insist she won't spend any more money indulging her daughter's obsession with the star, adding, "You might be too out of touch to grasp this, but surely you are surrounded by smart people who understand: I think you are a rude little kid, and I will not spend another cent supporting you. I feel confident I am not alone. You are alienating moms one concert at a time, and it is my hope that a year from now, the tax return you like to brag about will reflect that."

Bieber previously hit headlines on the U.K. leg of his Believe tour when he delayed the start of his concert at London's O2 Arena and left the young audience waiting for hours. He was subsequently forced to apologise.