Nicolas Sarkozy said his "frankness" and "free spirit" had led him to make errors during his 2007-2012 term as French president, in a book unveiled on Friday that is key to his bid for re-election in 2017.

It was a mistake telling a hostile bystander at a farm fair "Get lost, you jerk", and it was another error to have celebrated his 2007 election win on a French tycoon's yacht, he said in the book headlined "France for life".

The mea culpa on his abrasive style and efforts to counter the "President Bling-Bling" nickname he earned after the luxury boat trip address what were seen as key factors in his 2012 election defeat to Socialist Francois Hollande.

"It was undeniably a bad call. I'm still wondering today how I could make such a mistake," he said of the break on the luxury boat. It took him, he reflected, too long to "tame his character" and act as a president.

While Sarkozy has not publicly stated that he will be a candidate in 2017, the carefully timed release of the book, which also sketches out policy proposals, was widely seen as the opening salvo of a campaign.

"My character has always led me to be frank," Sarkozy writes in the book. "But with age and experience, I have learnt to calibrate that frankness," he said.

Opinion polls have shown over the past two weeks that a majority of French do not want Sarkozy back in office and rival Alain Juppe is more popular than he is as a conservative candidate for the 2017 presidential election.

The first hurdle towards the election is a conservative primary contest in November.

CUT TAXES, CURB MIGRATION

Outlining the broad lines of a policy programe, the 60-year-old who won power shortly before a global financial crisis and sharp economic downturn says in the book he should have moved faster to shake up the economy and would now roll back laws such as the one imposing a legal work week of 35 hours.

Abolishing France's wealth tax should be another priority, together with a 10 percent cut in income tax and ensuring that profit tax on corporations was no higher in France than the European average, he says.

Sarkozy also says in the book that despite his misgivings about a law that the Socialists introduced to legalise same-sex marriages, he would not seek to repeal the legislation.

He said France needed to better control migration "not to get submerged." "No work contract, no entry on (French) territory," he writes.

In the book he complains about getting bad press and says he has been unfairly targeted by judges. A string of judicial investigations into his election campaign financing have also hurt his ratings. He denies any wrongdoing.

While he devotes little of the 260 pages to his rivals in the conservative primary, Sarkozy criticises Hollande throughout.

"I know how good he is at manipulating and setting up traps," he says of Hollande. "He doesn't like making decisions. His world is one of friendly ambiguity."