Celebrities including Caitlyn Jenner, Katy Perry and Ariana Grande have taken to Twitter to voice their condemnation of President Donald Trump's announcement that he plans to ban transgender people from serving in the US military.

The shock policy decision was announced by the Republican President on Wednesday (July 26) in a series of tweets. It marks a sharp reversal from Barack Obama's administration's lifting of a similar ban last year which allowed transgender military personnel to serve openly.

Jenner, who voted for Trump and is a Republican party supporter, tweeted: "There are 15,000 patriotic transgender Americans in the US military fighting for all of us. What happened to your promise to fight for them?"

Trump previously voiced his support for the LGBT community, tweeting in June 2016: "I will fight for you while Hillary brings in more people that will threaten your freedoms and beliefs."

The President asserted in a series of tweets early on Wednesday that transgender people would not be allowed to serve in "any capacity".

He added: "Our military must be focused on decisive and overwhelming victory and cannot be burdened with the tremendous medical costs and disruption that transgender in the military would entail." 

A host of celebrities took to Twitter to voice their disgust at President Trump's decision, with many pledging their support to the LGBTQ community.