A QUIRKY film about a white Parisian woman who turns black has become the latest - and strangest - example of a new French obsession with the question of how to promote racial harmony.

From the watering holes of the intellos on the Parisian Left Bank to the corridors of parliament, the subject has shot to the top of the agenda in recent days, boosted also by Carla Bruni-Sarkozy, the first lady, who recently complained about politics, entertainment and business being dominated by a white male elite.

Last week a musical comedy became the unlikely focus of the debate as Agathe Cléry, a film starring Valérie Lemercier, one of the nation’s most popular comic actresses, held a mirror up to some of the ugliest aspects of French society.

Lemercier, 44, plays a racist cosmetics company executive who gets her comeuppance when, as a result of a rare skin complaint, she becomes black. She ends up losing her job.

The appearance of this unusual morality tale has coincided with a heated debate about whether the government should encourage racial equality in a society where, according to the constitution at least, all citizens are equal. The reality is that they are not, and although one critic has described the film as “in questionable taste”, none has questioned the premise of Agathe Cléry - that France is riddled with racism.

In the film Cléry complains that Paris is filled with Romanians, she calls her local corner shop “the Arab’s” and draws more nervous giggles from audiences by referring to flats in a rough area as having a “satellite dish on the balcony, Arabs in the sitting room”.

She gets a taste of her own medicine when her skin changes colour as a result of Addison’s disease. Her doctor tells her that she can expect to lead a normal life and that John F Kennedy, the former American president, suffered from a milder form, although “that didn’t stop him being assassinated”. Besides being forced out of her job, Cléry also loses her boyfriend. She is even threatened with eviction from her flat.

She applies for several other jobs on the strength of an impressive CV, but when she arrives at interviews the potential employers are shocked to find that she is black and trot out a series of excuses to avoid offering her the job.

The film is one of several to have focused recently on racial barriers and, as one critic put it, “the Paris of the excluded”, an issue that came to the fore three years ago in the worst street violence France had seen since the 1960s.

Since then the government has been pouring funds into poor immigrant suburbs, but with little effect: the rioting of 2005 was followed by violent outbursts a year ago in which a police officer was beaten almost to death and several buildings, including a police station, were burnt down in Villiers-le-Bel, just outside Paris.

In another crime-ridden suburb last month, Luc Besson, the director, had to suspend filming on From Paris with Love, a thriller starring John Travolta, when eight cars that were to have been used in a chase scene were set on fire. On an average Saturday night dozens of cars are burnt in suburbs all over France, according to police.

Even if the election of America’s first black president has given a lift to minorities, the failure of France’s model of integration is exemplified by the fashion, among descendants of immigrants, for dropping Christian names such as Louis or Laurent in favour of names such as Abdel or Said from their Arab or African backgrounds.

The Lemercier film is certain to fuel the debate with its look at both sides of the racism coin: Cléry ends up getting a job in a company run by black people, who turn out to be just as racist and refuse to employ any whites. Her boss is a black man whose CV she had once, in her previous racist incarnation, tossed into the bin.

He does not like it when she becomes white again, but by then they have fallen in love and, in an ending worthy of Hollywood, live happily ever after. If only it were that easy.

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