The giant US food group, Kraft Foods, has made a formal $US16.1 billion offer to Cadbury's shareholders, triggering a two-month takeover fight for the chocolate maker.
The offer also starts the clock ticking for potential rival bidders, such as US chocolate company Hershey, to make a counter bid.
Cadbury is reported as saying Kraft's offer remain derisory.
UK Business Secretary Lord Peter Mandelson says Kraft will face a backlash if it tries to buy Cadbury on the cheap.
But he admits there's little he can do, as financial markets are so open.
Cadbury's response is due in two weeks.
Analysts expect Kraft to increase its offer of cash and shares in order to ward off rival bidders and appease Cadbury's shareholders.
