Just a month after naming his team, Sarkozy switched the previous economy chief Jean-Louis Borloo to run a new energy and environment mega-ministry in place of Alain Juppe who quit the government after losing his constituency in Sunday's poll.

Ms Lagarde entered politics in 2005 as trade minister in the previous conservative administration and her assured handling of the brief meant she was given the tricky farms portfolio last month when Sarkozy unveiled his administration.

Her promotion to economy minister was something of a surprise, and she must now sell economic reforms to the sceptical unions and convince EU partners that tax cuts will not stop Paris respecting the bloc's rules on fiscal discipline.

Sarkozy also appointed 12 new junior ministers on Tuesday, drafting in figures from the centre, left and grass-roots groups, and naming French national rugby coach Bernard Laporte to become secretary of state for sport after the Rugby World Cup later this year.