(Reuters) - A documentary is in the works about the late British soul singer Amy Winehouse and it features previously unseen material, the film's distributor said on Wednesday. The film, which will include archival footage never seen by the public, will be directed by Briton Asif Kapadia, whose 2010 film "Senna," about Brazilian auto racer Ayrton Senna, won a BAFTA for best documentary. The Grammy-winning singer died in 2011 at the age 27 from alcohol poisoning. Winehouse's 2006 album "Back to Black" made her an international star. ...