Watch our Top Story: Sarkozy's mission to Mexico

The shadow of Florence Cassez, sentenced to 60 years in prison for her involvement with a kidnap gang, has cast a shadow over French President Nicolas Sarkozy’s visit to Mexico.

Sarkozy is to plead for Cassez’s transfer to a French prison, which has been complicated by her refusal to admit the charges against her.

Sarkozy and his Mexican counterpart Felipe Calderon discussed the “Cassez case” during a private meeting on Sunday.

At a press conference on Monday, Sarkozy said a working group must take a close look at the case, saying France and Mexico would respect its conclusions.

Mexican popular opinion is against transfering Cassez to France.

The left-leaning daily La Jordana went as far as to accuse France of “colonialist intervention” in the case.

Anthony Bellanger, correspondent for French daily the Courrier International, said Sarkozy, who promised Cassez’s father he would do “everything he could”, faces an uphill battle.

“Mexico is a huge country with an independent judiciary, which is one of the most trusted institutions in the country,” Bellonger said in a televised interview with FRANCE 24.

“The very fact that Sarkozy is in a position to negotiate this issue has caused outrage.”

Besides the Cassez case, Sarkozy and Calderon will make announcements on the consolidation of political and economic cooperation between the two countries.

They are expected to sign a series of accords on security and healthcare, as well as making a joint declaration on climate change and the reform of the G8 and the United Nations.