At least three of the UK's top-selling chocolate products still contain meat extract - despite a public backlash against Mars UK last year.

In May 2007, we revealed Mars had reformulated many of its bestselling lines to include animal rennet. The company was deluged with complaints from vegetarians when the news broke, prompting it to promise an astonishing about-turn. However, eight months on, Twix, Milky Way and Celebrations are still unsuitable for vegetarians.

Mars lines suitable for veggies now indicate this - but the Vegan Society has called for the company to display on-pack if a line is not suitable. "A full-size Mars bar is veggie-friendly, but a Celebrations one contains meat derivatives," said a spokesman.

Mars said it had no plans to remove the rennet from the three products, which are manufactured abroad.