Just days after her appointment, Oudéa-Castéra has faced calls to resign over her claim that she sent her eldest son to a private establishment because of teacher absences and staffing shortfalls at his public school in central Paris.

The minister was booed and heckled by protesters when she visited the school on Tuesday, saying she wished to "apologise" to staff members "offended" by her comments.

Oudéa-Castéra was one of the main winners in last week's cabinet reshuffle, with the former French junior tennis champion given the education ministry alongside her existing portfolio as sports minister.

Heading the new "super ministry", she will be leading preparations for the 2024 Olympics in Paris as well as handling one of the most sensitive issues in French politics.

But her tenure at the Education Ministry has been mired in controversy since she told reporters on Friday that she had moved her son to an elite private school because of "loads of teaching hours without a serious replacement" teacher at his public school.

She added that she was "fed up, like hundreds of thousands of families" across France.

All three sons of Oudéa-Castéra, who is married to the president of French pharma giant Sanofi, Frederic Oudéa, have attended the prestigious Stanislas school, a Catholic institution near her home in Paris.

The private school has been under investigation by the education ministry since last year over press reports of homophobic and sexist behaviour.

Adding to the minister's woes, left-leaning daily Libération reported Sunday that Oudéa-Castéra's son had not been affected by staffing gaps at the public school, citing the nursery school teacher who had his class in 2009.

The family in fact chose to move the child to the private school because the public one would not bump him up a year, the teacher said.

Oudéa-Castéra "categorically denies the claims reported by Libération," her office told AFP.

"We have to close this chapter of personal attacks and personal life," the minister said during a visit to another Paris school on Monday, adding that she had "tried to respond as sincerely as possible".

Teachers' unions – already fuming that education has been merged into a multiple ministry – and the political opposition have seized on the report to launch a broadside against the new minister.

"It's a double fault to the minister! This match is starting off really well!" said Guislaine David, spokeswoman for primary school teachers' union SNUipp-FSU, referring to Oudéa-Castéra's earlier tennis career.

The new minister is scheduled to meet education union representatives this week, her office said.

"If the minister really lied... (she) has no place at the head of the education ministry," Rodrigo Arenas, an MP for the hard-left LFI party and former head of a nationwide parents' federation, wrote on X (formerly Twitter).

The Oudéa-Castéra row has sucked the air out of Macron's hope that a new, smaller ministerial team around youngest-ever Prime Minister Gabriel Attal, 34, could help regain his administration's momentum.

Since his 2022 re-election, Macron has lost his parliamentary majority but still forced through unpopular reforms including an increase in the headline retirement age.

Ministers struggled late last year to push through a much-hyped immigration bill, eventually getting it over the line with major concessions to conservatives – including some measures the government has itself said are unconstitutional and may be struck down by the courts.

Read moreMacron accused of doing far-right’s bidding with stricter immigration law

Meanwhile the far-right National Rally looks set to beat Macron's Renaissance party handily in June's European Parliament elections.

"They've been in power for seven years and for seven years they've done nothing to get public schools back on their feet," far-right leader Marine Le Pen wrote on X on Friday.

"Now they're taking offence at schools' deterioration as if they weren't responsible," she added.

(FRANCE 24 with AFP)