Zac Efron has apologised for a ‘completely insensitive’ tweet he shared during Martin Luther King Day on Monday (January 18th). The 28 year old actor faced backlash online after posting the message to his 21 million social media followers, which has since been deleted.

zac efronZac Efron has apologised for causing offence with a tweet sent on Martin Luther King day.

Writing on Instagram Efron said: "I have nothing but the greatest admiration and respect for Dr. Martin Luther King Jr. I realize that last night's post was completely insensitive and I apologize to anyone who I may have offended. So sorry.”

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According to People, the now deleted tweet read: 'I'm grateful for a couple things today: Martin Luther King Jr & 10 million followers on IG,' and also included a raised fist emoji and pointing index emoji, both in black skin tone.

Many on social media immediately criticised the actor for sending the tweet, with one user telling him: ‘This is one of the most offensive/diminishing/disrespectful things anyone has said in relation to MLK today. Get over yourself.’

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Earlier this week Efron also upset fans when it was announced he would not be part of the High School Musical cast reunion airing tonight (January 20th) on the Disney channel. Cast members Vanessa Hudgens, Ashley Tisdale, Lucas Grabeel, Corbin Bleu and Monique Coleman have all reunited for a special sit-down interview, while Efron will appear via a ‘special pre-taped message’.