Kraft Foods Inc's offer for Cadbury Plc is unlikely to stay at its current level as the company brings its takeover campaign directly to the British confectioner's shareholders, a source familiar with the situation said on Monday.

Kraft, which made no effort to hold talks with Cadbury in recent weeks, turned hostile on Monday and refused to sweeten its $16.4 billion offer for Cadbury. Kraft has given up on getting an endorsed offer from Cadbury's board and instead will wage its takeover campaign directly with Cadbury shareholders, the source said.

Kraft's offer is unlikely to stay at this level at the end of the day, the source said.

(Reporting by Jessica Hall; Editing by Lisa Von Ahn)