Some of the UK's best-selling chocolate bars, such as Mars and Twix, will no longer be suitable for vegetarians, Also affecting brands such as Snickers and Maltesers, owner Masterfoods said it had started to use animal product rennet to make its chocolate products.
Masterfoods said it had started using rennet from 1 May and non-affected products had a "best before date" up to 1 October.
