Lambert, who said unions wanted assurances that France would defend its farmers' interests more robustly in Brussels, signalled protests could resume if talks with the government did not yield enough.
According to FNSEA head Christiane Lambert, the protest is aimed at exerting pressure on French authorities over recent trade deals that would give a green light to imports of meat, sugar and ethanol from states "that do not respect the same conditions of production as French products".
Agriculture Minister Stephane Travert said Monday that the government would not back down, adding that he would meet soon with unions as well as biofuels producers to discuss supplies and pricing.
Farmers in France have blocked access to several oil depots and refineries in protest - that is organized to last three days - against the proposed use of imported palm oil at a Total biofuel plant.
It urged clients not to rush to petrol stations to fill their tanks, which could spark panic buying and shortages.
Energy giant Total wants to import up to 300,000 tons a year of palm oil, which environmental advocates say has caused massive deforestation chiefly in southeast Asia.More news: Australia says end to South Korea-US war games not a certainty
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Total's decision was "the last straw", she said in an interview with Franceinfo television. Palm oil is cheaper than rapeseed oil.
Fuel shortages were not expected as a result of the blockade, given France's network of emergency fuel reserves and in the absence of sympathy action by fuel sector workers.
"We will commit at European Union level to cap, to freeze. based on the total 2017 volumes, the volume of imported (palm) oil to reduce it gradually in the coming years", French junior ecology minister Sebastien Lecornu said on Europe 1 radio.
Indonesia and Malaysia are the two largest producers of palm oil.
The company has said that no more than 50 percent of raw material used at the facility will be imported palm oil, and that all suppliers will be certified by the Roundtable on Sustainable Palm Oil.