Kraft CEO Irene Rosenfeld suffered a major setback this morning when billionaire investor Warren Buffett said he would not support her company issuing more shares in order to sweeten a bid for Cadbury.

Buffett’s investment company, Berkshire Hathaway, owns a 9.4 percent stake in Kraft, and observers have seen the Oracle of Omaha’s support as essential if Kraft is to go the distance in its pursuit of Cadbury.

The “no” decision by Buffett followed Kraft’s announcement this morning that it was tweaking its $16.3 billion bid for Cadbury by deploying more cash in its stock-and-cash offer.

It also comes as a potential rival, Nestle, officially took itself out of the running for Cadbury by agreeing to buy Kraft’s pizza business instead