A furious diplomatic row has erupted between France and Mexico over the fate of a Frenchwoman described as a "bloodthirsty, evil kidnapper" serving a 60-year jail sentence.
Despite the gravity of the crimes of which she was convicted, Florence Cassez has won the support of the French president, Nicolas Sarkozy, who is said to speak regularly to her by telephone.
Carlos Fuentes, a former Mexican ambassador to France and now one of his country's best-known novelists, has accused Mr Sarkozy of acting "like a banana republic dictator" by turning the case into an affair of state to improve his dismal poll ratings.
The Mexican government has said it will withdraw from a year-long French festival, The Year of Mexico, after the president said the event would be dedicated to 36-year-old Cassez.
Tensions between the two governments then heightened when the present Mexican ambassador in Paris, Carlos de Ciaza, stormed out of an official function in the French parliament's upper house, or Senate, after Mr Sarkozy's foreign minister Michèle Alliot-Marie mentioned the case in her speech.
The Mexican government's own foreign affairs ministry has expressed dismay that a head of state should take a decision affecting the peoples of two countries "in consultation with someone who has been convicted in Mexican law of particularly serious offences".
"We have been invited to a cultural event that has been turned into a homage to a kidnapper," the ministry added.
At first glace, Cassez - who has thanked Mr Sarkozy in a radio interview for his "magnificent" support - is an improbable candidate for the sympathy of a president who prides himself as being tough on crime.
Her conviction, upheld earlier this month, was for alleged involvement in the "Zodiacs", one of the gangs responsible for the brutal, sometimes murderous abductions that have plagued Mexico in recent years.
Two victims and one gang member identified Cassez as having played a prominent part in their detention and mistreatment. The Mexican authorities insist she has been fairly tried and found guilty of four kidnappings, association with criminals and possession of arms and ammunition.
Her initial sentence, passed in 2007, totalled 96 years but this exceeded the longest term of imprisonment available in Mexican law and was reduced a year ago to the 60-year maximum.
But Cassez, a native of Lille, northern France, who went to Mexico to work first for her brother, who deals in medical supplies, and then for a firm of architects, claims to be the victim of a spectacular miscarriage of justice.
She admits falling in love with the gang leader, Israel Vallarta Cisneros, but insists she believed him to be a car dealer and would have denounced him had she known of his criminal activities.
Her lawyers have unsuccessfully challenged her convictions on the grounds that they are based on suspect evidence, extracted under torture in the case of the gang member.
Cassez was arrested when stopped, in the company of Vallarta, on a motorway 50km outside Mexico City. But a police chief staged a reconstruction of the arrest for the benefit of television, purporting it to show she was detained at Vallarta's ranch, where it was claimed some kidnap victims had been held.
The defence claims this was a stunt designed, along with subsequent manipulation of witness testimony, to show the police were succeeding in the war against kidnappers.
Mexico has one of the world's highest kidnapping rates. The number of abductions lasting more than a few weeks rose from 564 in 2005 to 965 in 2008 according to official records and, in certain cases, victims have been murdered even after the payment of ransoms.
Mr Sarkozy and ministers share the concern of defence lawyers, and the imprisoned woman's family, that serious irregularities have been identified in the case against Cassez. But demands for her repatriation to a French prison, in accordance with an international treaty, have been rejected by Mexico, which fears her sentence would be cut or even cancelled in France.
The controversy has led to strong criticism of France and its president, in Mexico. It was in the Mexican press that Cassez was described as a "bloodthirsty, evil kidnapper", though some journalists have voiced unease with aspects of the case.
In France, opinion is divided between those who say the Mexican courts' rulings should be respected and others who believe in her innocence.
Mr Sarkozy's conduct has been called into question by several commentators.
One newspaper editorial accused him of acting "like an elephant in a china shop". Support has been rare, though the left-of-centre Libération, normally hostile to Mr Sarkozy, praised his humanitarian stance, adding: "it is difficult to reproach the president for concerning himself with the fate of a compatriot imprisoned in dubious circumstances in a foreign land."
The president himself is unrepentant. Shrugging off criticism, he said during a visit to the north-eastern French département of Marne that France remained an admirer of Mexican civilisation and friendly towards its people but added: "We will not abandon her … the time has come to keep our cool and obtain results and that is how I intend to occupy myself."