Agrochemical company Syngenta has rejected a takeover bid from its US rival Monsanto that valued the company at more than €40bn.

Syngenta’s board rejected the offer, saying it undervalued the business at a time when its valuation is currently under pressure from weak crop prices and currency headwinds.

If the takeover went ahead, Monsanto would have become by far the largest seed and chemical company in the world with a turnover close to €30bn, controlling some 40% of the global seed and chemical market.