A global shortage of the music-quality magnetic tape used in cassettes has helped the fortunes of two firms, riding the resurgence in popularity of cassettes.

Across the US cassette tape album sales grew by 23 per cent in 2018, according to industry tracker Nielsen Music. Sales rose from 178,000 copies the year prior to 219,000.

That may be small fry compared to the 1994 heyday, when sales of 246 million cassette albums were recorded. But, nevertheless, it is still significant considering the format was all but dead by the mid 2000s.

The revival meant that there was not enough magnetic tape to produce the required tape.

So two facilities - one in the American Midwest and the other in western France - have stepped in to meet the need.

"It's a good place to be - there's plenty of business for both of us," said Steve Stepp, who founded the National Audio Company in Springfield, Missouri with his father 50 years ago.

He said that around 2000 the "imperial hegemony of the CD" cut his business, which stayed alive as a major manufacturer of books on tape that remained popular.

Mr Stepp credits the eventual return of cassettes to rock bands like Pearl Jam and The Smashing Pumpkins, who began seeking to manufacture anniversary tapes in the mid-2000s.