A former mayor campaigning on an anti-corruption ticket swept to victory in El Salvador's presidential election on Sunday, bringing an end to a two-party system that has held sway over the violence-plagued Central American country for three decades.

Nayib Bukele, the 37-year-old former mayor of the capital, San Salvador, won 54 percent of votes with returns counted from 88 percent of polling stations, said Julio Olivo, the head of the electoral tribunal.

Bukele's two rivals from mainstream political parties conceded defeat. Definitive results would be announced within two days, Olivo said.