The deal could be announced as soon as Wednesday -- when Syngenta's results are published -- but it has not yet been finalised, Bloomberg quoted people familiar with the matter as saying.
If it goes ahead, the deal would outstrip the China Unicom Hong Kong Ltd.'s purchase of China Netcom Group Corp. In 2008, according to data from the organisation.
Syngenta declined to comment when contacted by AFP.
A week earlier, the state giant said it would buy Germany's KraussMaffei Group, which makes machinery for producing plastics and rubber, for 925 million euros (USD 1.0 billion).