France has been using strategic fuel reserves for two days in the face of widespread blockades of oil depots by union activists, the head of the oil industry federation said Wednesday.

"For the past two days, since there have been operational problems at the refineries and blockades of depots, we have... been using reserve supplies," Francis Duseux told French radio.

Authorities will continue to tap a day's worth of reserves every day "if the situation remains very tense".

"At the worst, if the situation remains very tense, we will do this for three months," Duseux said.

He added that consumers "contribute a little" to the problem because they were panic-buying.

"We are all filling our tanks as a precaution, because we are afraid, and the consumption is multiplied by three times or even five times in some areas," he said.