Lost digital artworks by Andy Warhol have been found on a batch of 30-year-old floppy disks.

The pieces include a digital doodle of his iconic Campbell's Soup painting and Marilyn Monroe pop art work plus a photographed portrait of Blondie frontwoman Debbie Harry that had been digitally manipulated.

The works are believed to have been created by the artist in 1985 to promote the graphic capabilities of a new computer.

They were discovered by students of Carnegie Mellon University in Pittsburgh, Pennsylvania who set out on a hunt for the pieces after one of their number found out about Warhol's involvement in the computer project.

The floppy disks, a storage method which has become obsolete in recent years, were found in the archives at the Warhol Museum in Pittsburgh, but the staff did not realise they contained the precious images as they could not access the data.

The 18 images were retrieved by experts at the university.

The journey to the discovery was filmed for a documentary, Trapped: Andy Warhol's Amiga Experiments, which will be shown in the city next month (May14).