A high school in California has warned students against chanting 'USA' at sporting events in case it offends students of 'different ethnicities'.

Lori Emmington, the principal of Vista del Lago in Folsom, California, sent an email to parents and made the announcement over the PA system on Thursday.

She suggested that it was appropriate for students to chant 'USA' after singing the National Anthem or Pledge of Allegiance but that if used at athletic events in any other way, it could risk sending an 'unintended message'.

'During an athletic event, when Vista fans are in a competitive environment and cheering their school pride, chanting USA might be confusing.

'What is the intent, and is it open to misinterpretation? What would be the purpose at a sporting event?' the email read.

While chanting USA has not been banned, staff said they wanted to encourage students to 'think through their decisions before choosing how to express themselves.'

Vista del Lago in Folsom, California, warned students against chanting 'USA' at athletic events unless it was directly before or after the National Anthem to avoid offending students of 'different ethnicities'

The announcement was prompted by recent guidance from the California Interscholastic Federation which reported 'rising concerns' about how students use the chant at events.

Last year, white fans waving Donald Trump and Betsy Ross 13 star flags chanted 'USA' throughout a game which was against a predominantly black high school in Michigan.

It prompted the area's sporting conference to ban crowds from chanting USA during the game.

Vista Del Lago's principal took the advice and used it to 'start a conversation' on the topic at a school leaders event but that many were confused by it.

They complained to their parents who later raised concern with the school, asking why it had banned the chant which they saw as nothing more than patriotic.

The email on Wednesday sought to clarify the confusion.

The email was sent to parents on Thursday after some complained when their children came home and said the chant had been banned. It has not been, but staff had tried to 'start a conversation' on when it might be appropriate

The school said that while the chant was appropriate after and before the National Anthem and Pledge of Allegiance, it may be 'confusing' if used at athletic events like football games

'First, I want to make clear that we have not prohibited students from chanting “USA” during athletic events or from expressing their patriotism while at school.

'At some schools throughout the country, the subject of patriotic chants has recently and increasingly caused concern in different communities after allegations that students were inappropriately taunting athletic opponents of different ethnicities. Here at Vista del Lago, we have not received any such complaints.

Principal Lori Emmington has not banned the chant despite confusion from students

'However, in our ongoing efforts to promote sportsmanship, empathy, and kindness, we have recently started a conversation with our students to ensure they fully think through their decisions before choosing how to express themselves,' it said.

Parents and students said the chant should never have been banned and that it unified students rather than divided them.

'I wasn’t angry, but I was definitely like, "Why can’t we chant USA?"' said senior Ryan Bernal told CBS Sacramento.

'To say USA, you know, we’re all the same. We’re all American. It doesn’t matter what your skin tone is or where you’re from,' senior Ryan Bernal said.

Others were outraged and confused and asked why, if there had never been a complaint at the school, the topic had been raised.

One former Marine said they were 'disgusted' by the 'PC police'.

'Last time I looked, this is still the United States of America where you say the Pledge of Allegiance, sing the National Anthem and pray to the God of your choice (or none for non-believers).

'We need to stop worrying about offending an individual and listen to the majority.'

'Unintended message? What, I love my country? I am proud to be an American? Seriously?' Shawn Huitt wrote on social media.

Senior Ryan Bernal said he was confused by the instruction from school staff and asked; 'To say USA, we're all the same. We're all American.' he said

Critics called the instruction 'crazy' and said it was proof of 'liberal America getting stupid'

'Liberal America is getting stupid! Kids can't openly show support for their own country because someone might get offended???' said someone else.

Former Republican Congressman Joe Walsh called school administrators 'cup cakes' and others called for them to be fired.

Some were confused by the concern and asked why students would use the chant when all players on both teams are American.

Since last year, there have been a spate of incidents at high schools across the country which involve students showing their support for President Donald Trump.

Some, who used his quotes in their yearbook, had them removed.

There have been criticisms that school staff are being over-cautious and that liberal-thinking teachers are censoring the youngsters' political views.

Alternatively, there was a spike in incidents of racial violence at some schools and universities in the weeks which preceded and came after the presidential election.

Pro-Trump Students shouted 'Heil Hitler!' at one school in Texas.