Sarkozy, 60, faces an uphill struggle as he tries to see off more popular members of his party, The Republicans, in order to make a new bid for the presidency in May 2017.

His new book, "France for Life", blames his defeat at the hands of Francois Hollande in 2012 on his failure to get tough on France's famously generous benefits and heavy taxes.

"Today, I regret delaying some reforms that should have been made in the first days of my presidency," writes Sarkozy, who ran the country from 2007 to 2012.

He admonishes himself for not challenging the 35-hour working week introduced by the Socialists in the late 1990s, or the "solidarity tax on fortunes" that targets the richest citizens but is accused by right-wing opponents of driving wealthy people out of the country.

Actor Gerard Depardieu and rock star Johnny Hallyday are among those who have left France in recent years to escape its hungry taxmen.