PARIS, Nov 26 (Reuters) - France will vote against a five-year extension of the licence for weed-killer glyphosate that the European Commission will propose on Monday, a junior French environment minister said.

The decision makes renewal more difficult for the product, which the U.N. health agency (WHO) has said causes cancer. Glyphosate is a key ingredient in Monsanto Co's top-selling weed-killer Roundup.

"The Commission will put one single proposition on the table on Monday: renewing glyphosate (licence) for five years. In view of the risks, France will oppose this proposition and vote against it," Brune Poirson said in an editorial in French Sunday newspaper Journal du Dimanche.

Fourteen out of 28 countries voted in favour of extending the licence when the EU voted on the issue on Nov. 9 with nine against and five abstentions. Under EU rules, 16 favourable votes are needed as a "qualified majority" for renewal before authorization expires on Dec. 15.

The Commission said after the Nov. 9 vote it would resubmit the proposal at the end of the month.

Glyphosate has been used by farmers for more than 40 years but its use was cast in doubt when WHO's cancer agency said in 2015 it probably causes cancer. The European Chemical Agency said in March this year, however, there was no evidence linking it to cancer in humans. (Reporting by Dominique Vidalon; Editing by Matthew Mpoke Bigg)