US pharmaceutical giant Pfizer could make a hostile bid for AstraZeneca as early as today.
Its £63 billion takeover offer was rejected after the UK company said it "substantially" undervalued the business.
That has forced Pfizer to consider its next move, with industry experts believing a hostile bid - which would aim to bypass the AstraZeneca management and target shareholders directly - could come soon.
Last week, Pfizer insisted it was committed to building a research and development hub in Cambridge which was planned by AstraZeneca.
The £300m base at the Cambridge Biomedial Campus would house about 2,000 researchers.
But a hostile bid would trigger increased calls for the offer to be referred to the competition authorities and would also heighten union fears over jobs if the takeover was successful.
US drugs giant Pfizer has said it is committed to building a planned research and development hub in Cambridge.
There were doubts over its future because of a possible £63 billion takeover of AstraZeneca, which had initially tabled the plans.
Pfizer has written to the Prime Minister confirming it's intention to see through with the project.
The £300 million base at the Cambridge Biomedial Campus will house about 2,000 researchers.