The recent campaign of violence and intimidation against the head of Novartis, the Swiss pharmaceutical group, is deeply troubling. It suggests that animal rights extremists are expanding and intensifying their terrorist tactics across Europe. The authorities must respond swiftly and firmly.

In the past few months, Novartis company property in France and Switzerland has been the target of violence. This week saw an apparent arson attack on an Austrian chalet owned by Daniel Vasella, its chief executive. This was followed by the most odious act to date: the desecration of the grave of Mr Vasella’s parents and the theft of his mother’s ashes.