"I hope this process will give the shareholders confidence in the underlying value of the company and support our clear view in rejecting the Monsanto proposals," said CFO, John Ramsay, in an interview with The Wall Street Journal.

Ramsay said the decision to put the business up for sale wasn't driven directly by Monsanto's approach, but followed a view that the U.S. company was undervaluing Syngenta's assets.

 “The Board and management are determined to accelerate shareholder value creation and our actions today underpin our commitment to do so. Our commitment is also shown by the significant capital return program that we announced today", said Syngenta's chairman, Michel Demaré.