Profits at Harry Potter publisher Bloomsbury rose 8% to £13 million last year, driven by a 133% surge in sales of JK Rowling's bestselling children's series.

Revenue grew 11% to £123.7 million as a special illustrated edition of Harry Potter And The Philosopher's Stone gave the firm a major boost.

Bloomsbury's children's division saw sales increase by 57% to £41.8 million as a result, compared with £26.6 million last year.

Chief executive Nigel Newton said: "Bloomsbury has had a very good year with strong revenue and book sales growth, including a significant increase in digital sales."

Digital revenues grew by 24% year on year to £5.3 million, which the company said is more than treble the industry growth rate.

However, turnover at its adult publishing division dipped from £36 million to £32.7 million as the firm announced the "Bloomsbury 2020 strategy", which aims to increase revenues from digital academic material.

Mr Newton added: "We have set out the Bloomsbury 2020 strategy. This focuses on growing revenues from academic and professional digital resources for academic libraries worldwide, whose budget is estimated to be 5 billion US dollars (£3.4 billion)."

The boy wizard's magic will be worked again this year, with Bloomsbury signalling the release of an illustrated edition of Harry Potter And The Chamber Of Secrets.