Pfizer’s talks to acquire botox-maker Allergan in a $150bn (€140.8bn) deal, the global drug industry’s largest ever, that would see the US drug giant re-domicile in Ireland accelerated yesterday, even as the US Treasury prepared to clamp down further on such tax inversions.

US medical device maker Medtronic Inc has said it agreed to buy Dublin-based Covidien Plc for $42.9bn (€31.6bn) and shift its executive headquarters to Ireland in the latest move by US firms to harvest lower corporate tax rates abroad.