US seeds and pesticides maker Monsanto is in talks with German chemicals giant BASF over a possible merger of their two agrochemicals divisions, Bloomberg News reported on Thursday quoting anonymous sources.

Acquiring BASF's agriculture solutions unit is just one of several transactions Monsanto is exploring as an alternative to a takeover offer from German chemicals and pharmaceuticals group Bayer.

"Discussions are at an early stage," Bloomberg reported, while "talks with Bayer are continuing" at the same time.

BASF's agricultural solutions division could be worth as much as 17 billion euros ($18.9 billion), analysts at DZ bank estimated on Thursday.

But they add that the German firm may not be tempted by Monsanto's offer, reportedly all in newly-issued shares rather than cash.

Talks between Monsanto and Bayer have been stalled for weeks after the German company refused to increase its initial offer of $62 billion unless it was allowed to look into the US firm's books -- which Monsanto said it would only agree to in exchange for a higher offer. 

Monsanto may face unrest among its shareholders if it chooses to buy up part of BASF rather than accepting Bayer's $122 per share offer -- which represents a 37-percent premium over the value of Monsanto's shares before the first media reports of a possible bid emerged.

BASF has also previously been rumoured to be interested in making a possible bid for Monsanto.

A BASF spokesperson told AFP on Thursday that the company would not comment on rumours.