Halewood International, owner of Crabbie's, believes the launches will generate new interest in the category, as well as enticing new customers.
The two extensions will be available in the take-home market.
The diet variant claims to have only one calorie per 100ml, while the twist of orange offering is to be marketed as a summer drink.
The bottles are being sold in 70cl "sharing" bottles and single-serve 330ml options.
Richard Clark, head of innovation at Halewood International, said: "The adult soft drinks market experienced significant growth in 2010 as consumers increasingly looked for alternatives to alcohol, due to health concerns and lifestyle choices, which have led to reductions in the consumption of alcohol both in the on-trade and take-home market.
"As experts in the ginger category since 1801, Crabbie's now has a varied product offering across multiple categories."
Crabbie's range of ginger drinks includes an alcoholic ginger beer, a cloudy ginger beer and a ginger mulled wine.
Crabbie's launched a World Cup campaign across radio in June 2010.