The long-time number two of French conservative politics, François Fillon, unexpectedly beat his former boss Nicolas Sarkozy in a presidential primary.

It was a huge blow to Sarkozy but not to the country's likely shift to the right, since Fillon shares Sarkozy's hard-line stance on immigration and security.

In the first round of the primary to elect the nominee for the centre-right Les Republicains party on Sunday, Fillon won 44 per cent of the votes, former Prime Minister Alain Juppe 28 per cent and Sarkozy 20 per cent, according to results from polls, published on Monday.