Harry Potter author JK Rowling is to receive a prestigious award from literary and human rights group PEN America.

Rowling will be presented with the PEN/Allen Foundation Literary Service Award on May 16 at the group's annual spring gala in New York. Previous winners include Toni Morrison, Sir Salman Rushdie and Sir Tom Stoppard.

PEN cited Rowling's advocacy for free expression, her founding of the charitable trust Volant, which supports multiple sclerosis research and other causes, and her non-profit organisation Lumos, which works to reconnect institutionalised children with their families.

"I'm deeply honoured to receive this award and humbled that my work has been recognised as having moral value by an organisation I so admire," Rowling said in a statement.

"I've long been a supporter of PEN, which does invaluable work on behalf of imprisoned writers and in defence of freedom of speech."

Rowling's own Potter books have been the targets of censorship and attempted censorship, with the fantasy series' feats of wizardry leading to worldwide allegations that the author advocates witchcraft and the occult.

PEN America president and prize-winning author Andrew Solomon said in a statement that Rowling's writing provides a wealth of "imagination, empathy, humour, and a love of reading, along the way revealing moral choices that help us understand ourselves".

"Through their experiences with Rowling both on and off the page, countless children have learned not only the power of speaking their own minds, but the critical importance of hearing others," Mr Solomon said.