French President Francois Hollande delivers the inaugural speech of the 2nd annual environmental conference in Paris September 20, 2013. REUTERS/Charles Platiau

PARIS (Reuters) - French President Francois Hollande saw his approval ratings fall to their lowest level so far in a monthly poll that showed less than a quarter of voters were satisfied with his actions.

In a survey by pollster IFOP published in weekly paper Le Journal du Dimanche, Hollande's approval ratings dropped 5 points from last month to 23 percent.

This was below his previous low of 25 percent in the same poll in April and close to the lowest ever score for a French president, the 22 percent recorded in 1991 by Francois Mitterand, France's previous Socialist president, the paper said.

The poll underlines the task facing Hollande in reviving his popularity at a time when wrangling over tax levels has clouded efforts to revitalize a sluggish economy and his support for military strikes against Syria has drawn mixed reactions.

The poll also showed Hollande's ratings among supporters of the Green party had slid by 19 points since last month, a sign of growing tensions between Hollande's Socialists and their Green allies in government.

Hollande this week outlined plans to slash fossil fuel use, supported by a new carbon tax, in an announcement seen as aimed at reassuring the Green party.

France's next presidential elections are due in 2017.

(Reporting by Gus Trompiz; Editing by Mark Potter)