Bosses of US drugs giant Pfizer have faced a second grilling from MPs over the company's proposed takeover of Astrazeneca.
The deal would result in the creation of the world's largest pharmaceutical company.
Andrew Miller, chair of the Science and Technology select committee, kicked off proceedings by asking why Pfizer and Astrazeneca would be a good match on the research side.
Mikael Dolston, president of worldwide research and development at Pfizer, said the deal would create a powerhouse of science, with the companies complementing each other in areas such as cancer drugs.
"Its not diversification its getting stronger where we are already strong", Dalston added.
Some MPs were curious as to why Pfizer was looking for such a major acquisition so soon after closing its research facility at Sandwich.
Pfizer's chief executive Ian Read said the company was now ready for a major acquisition.
When asked about how many scientists would be lost in the merger, Read said he could not give an exact figure.
He reiterated the company's commitment for 20 per cent of its global R&D headcount to be located in the UK. "We are not going to underinvest in the combined company", he added.
However, the Pfizer CEO confirmed that "the sum of the two will have less scientists".
MPs pressed the witnesses on what mechanisms there were to enforce the commitments Pfizer had given.
Read told the committee that in the event Pfizer broke one of its commitments, the Takeover Panel could refer the company to the high court. Read said Pfizer would submit the legal opinions it had received to the committee.
Miller asked whether the commitments to made to the Prime Minister were a negotiating position or final offer, to which Read replied "these were the commitments we were able to make".
MPs were told that Pfizer colleagues and employees were distressed about the way the proposed takeover had been portrayed in the media.
When members continued to press the witnesses on Pfizer's commitments to jobs and research a somewhat exasperated Read replied "I would like the commitee to tell me a commitment that Pfizer has not met."
Dolston hastily added that due to economic conditions in recent years Astrazeneca itself had been forced to downsize, along with much of the industry.
"I don't think there is a pharmaceutical company in the world that hasn't reduced employment", Read added.