PARIS (Reuters) - French centrist Francois Bayrou on Tuesday branded the liberal economic reforms floated by conservative presidential frontrunner Francois Fillon "dangerous" - remarks that may hint at an independent run that could damage Fillon's election hopes.

Bayrou, a pro-Europe politician who won 18.5 percent of first-round votes in the 2007 presidential vote, is backing ex-premier Alain Juppe's bid for the conservative nomination. But Juppe is now second-favorite in that race after Fillon's stunning win in the primary contest's opening round.

"The choices offered by Francois Fillon appear dangerous for our country," Bayrou told Reuters by telephone.

Fillon, an open admirer of right-wing Thatcherite economics, proposes cutting half a million public sector jobs to rein in government expenditure and wants less power for European Union institutions.

Bayrou refused to rule himself out from the presidential race. He said he continued to support Juppe and thought the mayor of Bordeaux could still win the conservative nomination.

A Bayrou candidacy would also complicate the election prospects of former economy minister Emmanuel Macron, who has launched an outsider bid that also targets the center ground.

An Ipsos/Cevipof opinion poll last week showed that Bayrou would win 11-12 percent of votes in next April's first round of the presidential election were he to run.

His support for leftist President Francois Hollande in 2012 is widely seen as having helped the Socialist candidate triumph over then-President Nicolas Sarkozy, who finished third in Sunday's conservative primary and was knocked out of the race.

(Reporting by Emmanuel Jarry; writing by Michel Rose; editing by Richard Lough/Mark Heinrich)