Sarkozy made a surprise visit to the African nation on Sunday and negotiated the release of three journalists and four Spanish flight attendants detained with the aid workers.
The charity workers, who had sought to fly 103 children they claimed were orphans from Darfur to France, face up to 20 years' hard labor if convicted.
The affair has been a diplomatic embarrassment for France and has strained relations with Chad, an ex-French colony where the European Union is planning to deploy peacekeepers along the border with Darfur.
French officials now say most of the children were Chadian and had living parents or close relatives.
Sarkozy, speaking during a visit with French fishermen before departing for the U.S., said he wanted to "go and get those who remain there, regardless of what they did."
"I prefer that they return," he said Tuesday. "It's the role of the chief of state to take charge of all the French whatever they are ... even if they have made mistakes."
The Belgian pilot of the plane, Jacques Wilmart, told reporters in Chad that he did not believe the charity workers acted illegally - but instead "did everything they could to save the children."
He and the plane's three Spanish crew members were being held on accessory charges. Lawyer Jean-Bernard Padare said in Chad that he filed for their release Tuesday and expected them freed within days.
Spain's foreign minister, Miguel Angel Moratinos, said he discussed the matter with his Chadian counterpart on Tuesday and that Spanish Prime Minister Jose Luis Rodriguez Zapatero spoke with Chadian President Idriss Deby on Monday. The French charity workers could be tried in France, according to a judicial agreement between the countries - if Chadian authorities agree.
But Chadian Justice Minister Albert Padacke said told RTL radio: "It is not up to President Sarkozy to decide what Chadian judicial authorities will do."
Chad's interior minister, Ahmat Mahamat Bachir, said allowing the charity workers to be tried in France "would constitute an insult to the Chadian people. That is why these bandits will be tried and convicted here."
"Once they have finished their sentences, we will expel them from the country once and for all," the French daily Le Parisien quoted him as saying.
He said Chad's justice system is capable of conducting a fair trial. He also said Chad would strengthen monitoring of aid groups, demanding monthly reports of their activities, according to Le Parisien.
The charity workers are already under legal scrutiny at home. French judicial officials said the group's leader, Eric Breteau, misled investigators in France and ignored warnings that his activities could be illegal.
Breteau also claimed - wrongly - that his group was cooperating with UNICEF, and that the group's subsidiary in Chad was a separate U.S. organization, judicial officials said. They spoke on condition of anonymity because they were not authorized to talk to the media.
French investigators were alerted to the activities of the group, called Zoe's Ark, in July, and questioned a dozen people in August about plans to "rescue" Darfur refugee children.
The investigators said they warned him that bringing the children for adoption in France could be illegal. Breteau signed the warning, acknowledging receipt, but went ahead.
Despite French officials' concerns, no measures were taken to stop the group.
It was unclear how the group planned to deal with the children's legal status once in France.