Mars could be poised to resurrect its Marathon brand after 18 years off the shelf in the latest move to cash in on retro brands.

Marathon was ditched in 1990 after Mars decided to align the UK branding with the global Snickers moniker. However, in the same week that Mars announced it was bringing back Opal Fruits as a three-month limited edition, the business also re-registered the Marathon brand as a trademark in the UK.

A retro rebrand would gain Mars valuable column inches in the national press, along the lines of the mass coverage Opal Fruits received last week and the widescale coverage that Cadbury gained last year when it brought back Wispa, which is now understood to be returning as a permanent countline.

But the move could confuse shoppers, said Rune Gustafson, chief executive of Interbrand.

"If it is treated as a limited edition then it's tactical marketing to create a buzz around the brand," he said.

"It can't, however, be a substitute for innovation . It is essential sales of the mother brand are not cannibalised and old consumers are brought back instead. Essentially, they're taking the focus off the global brand in which they've invested millions of pounds," he added.

But Jeffrey Hyman, chairman of The Food & Drink Innovation Network, said it was still clever marketing. "As a strategy it's excellent as it appeals to many older consumers ," he said.

Mars insisted there were "no immediate plans" for another retro rebrand in the wake of Opal Fruits.