Ice Cube claims he's finding it difficult to cast the right actors in the 'Straight Outta Comptom' movie.

The rapper has been working on the N.W.A biopic about the iconic 80s hip hop group and has spent months trying to find the right stars to play the lead parts.

He told ''We've been casting for six months now, so we're still in that process of finding the right people to represent the world's most dangerous group.

''We're telling the story from the inception of NWA to the death of [rapper] Eazy-E, that's the story.''

The parts of Dr. Dre, Ice Cube, DJ Yella, Mc Ren and Eazy-E, who died in 1995 of AIDS-related pneumonia, are all expected to be cast.

Ice Cube is producing the film along with Dr. Dre and F Gary Gray will direct.

Asked if the film would be better as four-hour miniseries than a two hour film, Ice Cube said: ''I would love for it to be a miniseries because there's so many nooks and crannies to the story but it's a feature film and we'll try to tell the story - not try, we actually will tell the story within that two [to] three hour time period.''

He added: ''We will be filming this year, definitely. We're schedule to film and start production in July.''