Monsanto, Syngenta said to be close on deal price

At least one major investor, hedge fund manager John Paulson, believes the agricultural giant Monsanto and Syngenta, the Swiss pesticide company it offered to buy in May, continue to be in deal talks and aren't far apart on price, according to someone who has been briefed on the matter.

Paulson, who reportedly took a small stake in Syngenta in recent months, would likely use that position to support a Monsanto purchase if the economics were attractive, this source said. Paulson met recently with the Swiss company's management and thinks they could be receptive to an improved deal, added this person.

The existence of Paulson's Syngenta stake and his likely support for the deal were first reported by Bloomberg News.

Fabrice Coffrini | AFP| Getty Images

Indeed, a survey of almost 100 fund managers conducted recently by Bernstein Research suggested that a number of Syngenta shareholders support the deal in principle—but would like to see a price premium of at least 5 percent above the $45 billion Monsanto has already offered.

Read MoreNo plans to acquire Syngenta: Bayer CEO

Sara Miller, a spokeswoman for Monsanto, declined to comment on the Paulson involvement, but said the company believes there is broad-based support for the strategic rationale behind a deal. "We look forward to advancing these conversations," she added.

A spokesman for Syngenta could not immediately be reached.