Fans expecting a Harry Potter fix this autumn will have to wait an extra nine months before they can see Harry Potter and the Half-Blood Prince, the sixth film in the series based on J.K. Rowling's best selling novels.

Warner Brothers have decided to move the release of the film from 21st November 2008 to 17th July 2009, despite star Daniel Radcliffe appearing on the cover of this week's Entertainment Weekly Fall Movie Preview.

"Like every other studio, we are still feeling the repercussions of the writers’ strike, which impacted the readiness of scripts for other films — changing the competitive landscape for 2009 and offering new windows of opportunity that we wanted to take advantage of," Warner's Alan Horn explained.

The final two movies, based on the last book in the series, will still debut in the autumn of 2010 and summer of 2011 as originally planned.