MPs are to question officials from US pharmaceutical giant Pfizer over its takeover bid for AstraZeneca.
The Business, Innovation and Skills Committee will also question officials from the UK-based firm, which has rejected a £63 billion takeover offer.
The committee is likely to seek assurances from the US firm about job security if the takeover goes ahead.
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Unions called for an urgent meeting with Business Secretary Vince Cable to press the case for jobs, amid speculation that Pfizer could be planning to make a hostile bid.
Unite assistant general secretary Tony Burke said: "The workforce and the unions have acted in a responsible manner and shown remarkable patience, but that is now wearing thin. Ed Miliband's sensible intervention at the weekend for a national interest test should be acted on. Neither the German or the French governments would be simply waving through a takeover on this scale.
"AstraZeneca is a key player in the UK's advanced manufacturing sector and as such is strategically important to the UK. Yet David Cameron and George Osborne seem comfortable waving the deal through, leaving any manufacturing strategy in tatters. Cameron says he has assurances on jobs and the future of the UK plants and we would like to know what they are.
"Smelling a quick profit, City institutions are now also pressing AstraZeneca to sit down and agree a deal with Pfizer. The companies should be talking to their workforces, as they would have to do in other countries before any deal goes through."
Mr Cable has indicated he is considering reforms to the "public interest test" for corporate takeovers amid a political row over Pfizer's move for AstraZeneca.
Mr Cable said the Government had been "looking at the options around the public interest test" after Labour leader Ed Miliband demanded a full assessment of the potential deal.
The Labour leader has written to David Cameron calling for the publication of any analysis the Government has made of the proposal and claimed the Prime Minister had been acting as a "cheerleader" for the proposed deal.
He proposed widening the scope of the public interest test to take in industries of strategic importance - such as the high-value scientific research carried out by AstraZeneca.
The Government can currently intervene on mergers or takeovers where there is a national security issue, an issue of media plurality, competition concerns or if it could affect financial stability.
Asked about reviewing the test, the Business Secretary said: "Obviously we are looking at this option amongst others, I'm sure you wouldn't expect me to go into all the detail and the discussions we are currently having between the two parties to the proposal.
"What we are endeavouring to ensure in the Government is to make absolutely sure Britain's excellent science base and pharmaceutical research is properly protected, manufacturing in the UK, decision-making, those are the issues we are talking to the companies about."
Mr Cable said he had spoken to the chief executives of both firms and stressed that the Government was "strictly neutral" between the two.
Mr Cameron has said the Government had received "robust" assurances from Pfizer about protection for British jobs and research under the proposed deal and stressed it was a decision for shareholders.
The Liberal Democrat Business Secretary said there was a "lot of small print to study" in the assurances given by Viagra manufacturer Pfizer.