BRUSSELS (Reuters) - EU countries hit deadlock on Thursday on the future of weed-killer glyphosate that some experts say causes cancer, with the European Commission urging them to reconsider its proposal to allow its use to continue for five years.

Europe has been wrestling for two years over what to do with the chemical, a key ingredient in Monsanto Co’s top-selling weed-killer Roundup.

The chemical has been used by farmers for more than 40 years, but its use was cast in doubt when the World Health Organization’s cancer agency concluded 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. A large long-term study published on Thursday of agricultural workers in the United States also found no link.

On Thursday, the European Union’s 28 countries failed to approve or reject the Commission’s proposal for a five-year extension to the license allowing glyphosate to be used.

Fourteen countries voted in favor, nine against and five abstained, not enough to secure a “qualified majority” under EU voting rules, the Commission said, adding that it would resubmit its proposal in the next two weeks, before the current authorization expires on Dec. 15.

In theory, the Commission could then push through the extension but it would prefer the governments make the call on an issue that has become politically charged.

France said it would push for a renewal of just three years.

“For the moment we have brought round a certain number of countries towards this objective, not enough yet,” French Environment Minister Nicolas Hulot told journalists. “Maybe we have to wait a few more weeks.”

The European Parliament has called for glyphosate to be phased out over the next five years. Environmental group Greenpeace said the EU should ban it immediately.

EU states failed twice in October even to vote on a proposal for a 10-year license extension.

French pollster Ipsos said in a study in September that a ban on glyphosate could cost the French grains sector, the EU’s largest, 1.1 billion euros ($1.3 billion) and wine producers 900 million euros due mainly to lower yields and a fall in exports.

Total EU sales of glyphosate-based products are around 1 billion euros per year. Monsanto has a share of about 40 percent of the global market.