Sheffield International Documentary Festival 2008 opened with the world premiere of Thriller In Manila, a documentary about boxing legend Joe Frazier. Director John Dower introduced his documentary and took part in a Q & A session after the screening.

Over the next four days, the festival will host international documentary makers and screen over 140 documentary films from over 20 countries.

Speaking to Screen International, festival director Heather Croall said the conference sessions will be one of the festival highlights. 'The conference sessions are always stellar. The quality of the sessions is mind blowing. I'm always impressed at the debate here at Sheffield.'

One of the sessions is entitled 'Theatrical Documentaries R.I.P.'' leading Croall to comment, 'The question mark at the end is very important. To me there is no question of R.I.P. The new media platforms offer more opportunities for documentaries.'

Other highlights of the festival will include master classes with award-winning documentary makers Nick Broomfield and Molly Dineen and an interview with Academy Award-winning director Ross Kauffman.

Andy Burnham, Secretary of State for Culture, Media and Sport will give the keynote interview later today.

BRITDOC, the documentary festival held in July since 2005 by the Channel 4 BRITDOC Foundation, will no longer run as an annual event. Instead it will go on the road, joining forces with major festivals across the world.

It has partnered up with Sheffield Doc/Fest and will screen films from the foundation's film-makers and will host a session on using film to create positive change in the world.