Polls opened in the Philippines on Monday in the country's most divisive presidential election in decades, with the prospect of a once-unthinkable return to rule of the Marcos family, 36 years after they were toppled in a "people power" uprising.

The election pits Vice President Leni Robredo against former senator and congressman Ferdinand Marcos Jr (above), the son and namesake of a dictator whose two-decade rule ended in a public revolt and his family's humiliating retreat into exile.

Opinion polls put Marcos, popularly known as "Bongbong", leading his rival by over 30 percentage points, having topped...