Johnny Cash biopic Walk the Line has boosted the country star's popularity, with CDs sales soaring by more than 700 per cent.

The A THING CALLED LOVE hitmaker, who died in 2003, is selling more music now than he ever did during his 50-year career, thanks to Joaquin Phoenix and Reese Witherspoon's evocative performances in the Oscar-nominated movie.

Music giant HMV reports Cash's RING OF FIRE album to be the most popular CD purchase.