The French government has said it will seek the repatriation of the six members of the aid group Zoe's Ark.
Under the terms of a judicial cooperation agreement they would be allowed to serve their sentences in France.
France does not force prisoners to perform hard labour.
Yesterday they were sentenced to eight years hard labour for attempting to kidnap 103 African children and fly them out of Chad to Europe.
Chad says it would have to approve any relaxation of the sentences of the activists if they are repatriated to France.
The six members of the aid group were arrested in October.
The rapid conclusion of the trial, which opened less than a week ago, has led to media speculation in France that a deal between the two governments has already been struck.
Zoe's Ark is an independent organisation formed in 2004 to help provide relief during the Asian tsunami. It is believed to have about 50 active volunteers.
The Chad operation, which the group said was planning to secure a better future for children orphaned by the war in Darfur, was widely condemned as amateurish in France but there was shock at the severity of the sentences.
The incident has angered many in Chad who saw the operation as a continuation of the colonial policies of their country's former ruler France.
