The Commons Science and Technology Committee said the promises made so far by Pfizer, which are limited to just five years, were of "little value" in an industry which measures progress in decades rather than years.
The committee is one of two cross-party House of Commons select committees to have taken evidence this week from the bosses of the two firms regarding the takeover, which is being strongly resisted by AstraZeneca.
In a letter to Science Minister David Willetts, who also appeared before the committee, the MPs said that, given the importance of AstraZeneca to scientific research in the UK, it was essential the Government obtained further "longer-term guarantees" from Pfizer.
"Science is a long-term enterprise and it requires a genuinely long-term commitment. We are not yet convinced that this is what Pfizer is offering," the committee said. "If Pfizer is as committed to the UK as it claims, we hope that it will voluntarily strengthen - and lengthen - the promises that it has made. But the Govern-ment must be willing - and, crucially, able - to hold Pfizer to account if necessary."
While ministers on both sides of the coalition have insisted the Government is "neutral" regarding the takeover, which is ultimately a matter for AstraZeneca's shareholders, LibDems including Business Secre-tary Vince Cable have emph-asised they have the power to intervene if necessary.