A major Cadbury shareholder has indicated that the US food company Kraft will have to increase its offer if it wishes to win support for a hostile takeover bid.
Legal & General Investment Management, which owns 5% of Cadbury shares, said Kraft's current offer did not meet "the long term value" of the UK company.
Kraft has until Tuesday to increase its offer to Cadbury shareholders. The current bid is worth less than Cadbury's share price.
Kraft is currently offering Â£10.5 billion, or 761 pence per share. This compares to Cadbury's Friday closing share price of 793.5p.
Earlier this week, Cadbury reiterated that its shareholders should reject Kraft's takeover bid.
The company said its financial performance last year was well ahead of market expectations.
Kraft launched a hostile takeover bid for Cadbury in December. It has until 19 January to decide whether to raise its offer.
If its final offer is rejected, Kraft will then have to wait another year before it can bid again.
Kraft remains the only current bidder for Cadbury, after Nestle ruled itself out. Hershey has previously expressed interest in a possible bid.