Talk of a $100 billion bid by US drugmaker Pfizer for its British rival AstraZeneca is "a commercial matter between the companies", Britain's finance minister George Osborne said today.

Shares in Britain’s second biggest drugs group hit record highs this week on the bid speculation. Both companies have declined to comment on a weekend newspaper report that AstraZeneca spurned an approach from Pfizer earlier this year.

Several analysts believe Pfizer may be tempted back by AstraZeneca’s pipeline of cancer drugs, as well as the potential to cut costs and make use of cash accumulated through foreign subsidiaries that would be taxed if repatriated to the US.

Asked about the matter after delivering a speech on the economic importance of Britain’s science base, Mr Osborne said the reports were speculative and declined to comment on any possible government involvement.

“It’s a commercial matter between the companies,” he said. “I note that AstraZeneca has not put out any market statement, which is something people’s attention should be drawn to, but I don’t think I should comment further on that commercial matter.”

Acquiring AstraZeneca would be the biggest ever foreign takeover of a British company and the suggested deal has triggered worries about jobs in Britain’s pharmaceuticals sector, which is viewed as a key industry by the government.

The healthcare sector is in the middle of a wave of deal-making, with Novartis and GlaxoSmithKline this week agreeing to trade more than $20 billion worth of assets and Zimmer agreeing to buy rival orthopaedic products maker Biomet for $13 billion.

Valeant Pharmaceuticals, meanwhile, is in a $47 billion bid battle to buy Botox maker Allergan. (Reuters)