EU finance ministers will start voting Friday on a nominee to replace France's Christine Lagarde as the head of the International Monetary Fund (IMF), the French Economy Ministry said.

The ministers agreed in a conference call Thursday that with no consensus as yet for any of the five identified candidates, it was time to hold one or more rounds of voting, the ministry said.

The Washington-based IMF is traditionally led by a European, while its sister institution, the World Bank, is led by a US national, although emerging countries have recently challenged this unwritten rule.

The vote is being delayed until Friday to give British Prime Minister Boris Johnson's new government a chance to nominate a sixth, British candidate if it so wishes.

The five candidates under discussion as of Thursday were Spanish Economy Minister Nadia Calvino; Portuguese Finance Minister Mario Centeno; former Dutch finance minister Jeroen Dijsselbloem; the World Bank's Bulgarian chief executive officer Kristalina Georgieva; and former EU commissioner Olli Rehn from Finland.

French Finance Minister Bruno Le Maire has been trying to find a European consensus on Lagarde's replacement after the IMF chief was tipped to head the European Central Bank.

The voting process will be held under the EU's weighted majority rule, which requires the approval of at least 16 of the 28 member states, representing at least 65 per cent of the total EU population.