"France will vote against a re-authorisation of glyphosate for 10 years given the uncertainties that persist with regard to its dangerousness," the source in the ecology and sustainable development ministry told AFP.
The opposition of France could block obtaining the qualified majority of EU member states needed to renew the licence.
Glyphosate is the active ingredient in the best-selling herbicide Roundup produced by the US agro-chemicals giant Monsanto, but there have been concerns it may cause cancer.
But in March, the EU's chemicals agency said glyphosate should not be classed as a carcinogen.
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And in May, a review carried out by experts from both the WHO and the UN Food and Agriculture Organization said "glyphosate is unlikely to pose a carcinogenic risk to humans from exposure through the diet".
On the basis of that research, the EU Commission proposed renewing the licence, which is scheduled to expire at the end of this year.
In June, more than one million people signed a petition in June, demanding the EU ban glyphosate.