The new arrival - an impulse pack that contains three balls in caramel, nougat and crispy chocolate flavours - is getting a £4.2m marketing push, the company's biggest launch this year.
"It is likely to be one of the launches of 2007," said Richard Brittle, purchasing director of Hancocks Cash & Carry. "The packaging is superb and the flavours are good. The fact there's a special version for independents is also good."
Masterfoods is targeting the bitesize market, which it values at £411.7m, because it is one of the few growth areas left in confectionery, thanks to demand for indulgence in smaller portions.
It aims to capitalise on last year's growth from the Mars brand, which outperformed the total chocolate confectionery market.
The Grocer's Top Products Survey 2006 (16 December) revealed the market as a whole dropped 1% year-on-year, while Mars grew 6%.
The brand extension underscores the power players' reluctance to bring new brands to the market, instead preferring to build on the heritage of already established names.
Masterfoods previously extended Mars into dark chocolate with a limited edition Mars Midnight, which launched four years ago and into female-oriented lines with Mars Delight two-mini-bar packs a year later.
Mini bars of the parent brand and Mars Delight were launched in cube boxes last Christmas.
Support activity will include a £3m TV ad campaign breaking in April as well as £1m in trade support including sampling.
Andrea Taylor, Trade Relations Manager at Masterfoods said: "We believe Mars Planets will drive the bitesize category and increase total confectionery sales for retailers."