The Archbishop of Canterbury has spoken out after a death threat was made against JK Rowling.

The Harry Potter author was threatened after tweeting her support for Sir Salman Rushdie, who was attacked in Chautauqua, New York state, on Friday.

Rowling tweeted: "Feeling very sick right now. Let him be ok."

In response to her post, a Twitter user replied, "Don't worry you are next."

Rowling said she is working with the police after the threat. 

"To all sending supportive messages: thank you. Police are involved (were already involved on other threats)," she posted later.

The Archbishop of Canterbury, Justin Welby, has strongly criticised the death threat against Rowling, saying that it undermines vital freedoms.

"It is appalling that there are threats to JK Rowling after her support for Salman Rushdie," he said.

"Threats and attacks undermine the freedom on which we all rely to be able to comment. Prayer and much sympathy for both."