SANTIAGO (Reuters) - Former Chilean President Ricardo Lagos said on Friday that he will run again for the country's highest office in 2017, possibly pitting the center-left politician against another ex-president, conservative Sebastian Pinera.

Lagos, 78, led the Andean nation from 2000 to 2006. He said in a statement that he wants to give continuity to reforms the ruling center-left coalition has implemented.

Socialist President Michelle Bachelet's government has introduced sweeping changes to the tax code, education and the electoral system.

But a series of scandals around politicians financing their campaigns with illegal contributions and allegations of dubious business dealings by her daughter-in-law have sapped Bachelet's political capital, while reduced tax revenue due to a sluggish economy have made it harder to pay for the reforms.

Bachelet, who is facing historically low approval ratings, has been forced to curtail her ambitious reform agenda.

"The great challenge is to give continuity to and improve the reforms the country has implemented, addressing the difficulties that exist," said Lagos.

A survey by pollster Gfk Adimark released on Friday showed that 18 percent of respondents said they would prefer Pinera to be reelected president next year, followed by 5 percent who preferred Lagos.

Pinera, president from 2010 to 2014, has yet to officially announce whether he will run for reelection, though he has said he could make an announcement on the matter early next year.

(Reporting by Anthony Esposito; Editing by Frances Kerry)