Almost £700m was wiped off the market value of Anglo-Swedish giant AstraZeneca after it said a European patent covering the use of its Symbicort drug had been revoked.

Shares in the Cheshire-based company, led by chief executive David Brennan fell 2.21 per cent, or 47p, to 2080p.

It said the decision followed an appeal from generic manufacturers Norton Healthcare and Generics UK.

AstraZeneca said the patent was one of two covering Symbicort - which is mainly used to treat asthma - and that the second was also being disputed. Mr Brennan vowed to defend AstraZeneca's intellectual property rights protecting the drug.