On the day when both company's chiefs were being quizzed by UK members of parliament, AstraZeneca has criticised US pharmaceutical rival Pfizer for what it said was an undervalued and 'opportunistic' takeover bid."The board of AstraZeneca believes Pfizer is making an opportunistic attempt to acquire a transformed AstraZeneca, without reflecting the value of its exciting pipeline," a statement from the Anglo-Swedish company said. "This value should accrue fully to AstraZeneca shareholders." "The board reiterates its confidence in AstraZeneca's ability to deliver on its prospects as an independent, science-led business."The statement noted a regulatory news service (RNS) announcement made by Pfizer earlier on Tuesday, which it said contained "no new proposal nor substantive new information".Pfizer was actually forced to reissue a previous announcement about its bid offering "compelling shareholder value" because it had neglected to add disclaimer footnotes on the first version of the statement. Ian Read, Chairman and Chief Executive of Pfizer, appeared before MPs on Tuesday to answer questions on the US company's plans for AstraZeneca should its bid be successful, with Pascal Soriot, Chief Executive AstraZeneca, following.OH