Two of France's former prime ministers will go head-to-head in a runoff vote for the country's centre-right presidential nomination.

Francois Fillon and Alain Juppe, both from Republicans Party, managed to oust former president Nicolas Sarkozy in the first round of primaries. The conservative rivals have clashed over their vision for France.

Frontrunner Fillon has promised radical reforms to the country's regulation-encumbered economy and a massive job cut. The more moderate Juppe attacked the "brutality" of his rival's reform program. Many French citizens view Sunday's contest as a proxy for next spring's presidential election.