German drugs and chemicals group Bayer AG made an unsolicited takeover offer for U.S. seeds company Monsanto Co, aiming to create the world's biggest agricultural supplier and integrate pesticides and seeds markets.

Monsanto disclosed the approach on Wednesday before Bayer confirmed its move, though neither gave the proposed terms. Sources said Bayer would pay Monsanto shareholders with cash and stock, though the offer price could not be learned.

Bernstein Research analyst Jeremy Redenius estimated the price at €41.9 billion ($47 billion), plus €6.7 billion in assumed debt. He said Bayer might need a €27 billion share issue to help to fund the purchase.