(Adds Sarkozy-Deby phone call paragraphs 8-9)

By Stephanie Hancock

ABECHE, Chad, Nov 1 (Reuters) - Chad's president said on Thursday he hoped some French and Spanish nationals detained for trying to fly African children to Europe could be freed soon, as U.N. officials said many of the infants were not orphans.

The central African country is holding nine French nationals, including two journalists, and seven Spanish air crew after blocking an attempt by French charity Zoe's Ark to fly out 103 children for foster care by European families.

U.N. officials said information from Red Cross interviews with the children contradicted statements by Zoe's Ark, which said they were sick and destitute orphans from Sudan's war-torn Darfur region.

"They are not orphans and they were not sitting alone in the desert in Chad, they were living with their families in communities," Annette Rehrl of U.N. refugee agency UNHCR told Reuters in the eastern Chadian town of Abeche.

Zoe's Ark, which has denied any wrongdoing and said it was operating under international law, was not immediately available for comment. Some of the families in Europe said they had paid up to 2,000 euros or more as a "donation".

Speaking to reporters in Abeche, Chadian President Idriss Deby promised a quick investigation and held out the possibility that some of those arrested might soon be released.

"I hope for my part that the Chadian justice system can quickly shed light on this and that the journalists and also the (Spanish) hostesses will be freed as quickly as possible. But I can't force the hand of Chadian justice, there is a procedure."

Deby said he had spoken by telephone on Wednesday with French President Nicolas Sarkozy, who has called for the release of the journalists, and the two men spoke again on Thursday.

"The call took place in an extremely positive atmosphere," Sarkozy's spokesman, David Martinon, said.

The French have been charged with abduction and fraud and face possible forced labour terms of up to 20 years if convicted. A Spanish pilot, a Belgian pilot and six Spanish crewmembers of the plane have been charged as accessories.

Deby was less hopeful about the quick release of the Spanish pilot, saying he believed there was "complicity".

"NO IMPACT ON RELATIONS"

Deby said the case would not hurt relations with former colonial power France, which has troops stationed in Chad and is due to provide the bulk of a European Union peacekeeping force to be deployed soon in the east.

"France as an official entity has nothing to do with this affair," Deby said.

Officials from the UNHCR, the U.N. children's agency UNICEF and the International Committee of the Red Cross have been caring for the children, 21 girls and 82 boys aged between one and 10 years, at an Abeche orphanage.

"During interviews with humanitarian staff, 91 children said they had been living with their families consisting of at least one adult they considered their parent," the agencies said.

Children who lose their parents in Africa are often taken in by other family members.

Some of the children have told journalists their parents were alive and they were lured from villages on the Chad-Sudan border in recent weeks with offers of sweets or schooling.

"Six people came to the village, including four French. Two of them were women. They told us 'We are taking your children to Abeche to go to school, we will bring them back in one week'," Halimi, a widow whose three children were among 13 children taken from a village in Tine district, told reporters in Abeche.

She said she spent six days travelling to Abeche after hearing about the Zoe's Ark children on the radio last week.

The case has triggered outrage among Chadians, with many on the barren border with Sudan questioning the motives of scores of foreign aid groups that work with Darfur refugees.

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