Costa Rica's ruling National Liberation Party presidential candidate, Laura Chinchilla, waves to supporters as she celebrates after winning the general elections in San Jose on Sunday. Photo: AFP

Costa Ricans have elected their first woman president as the ruling party candidate won in a landslide after campaigning to continue free market policies in Central America's most stable nation.

With most of the votes from Sunday's election counted, Laura Chinchilla held a 22-point lead over her closest rival. Her 47 percent share of the vote was well beyond the 40 percent needed to avoid a run-off.

The 50-year-old protege of the current president, Nobel Peace Prize laureate Oscar Arias, promised to pursue the same economic policies that recently brought the country into a trade pact with the US and opened commerce with China.