Ten U.S. Baptist missionaries charged in Haiti with child kidnapping should be allowed to leave the country pending the outcome of their case, their Haitian lawyer argued before a judge Friday.

Prior to the closed hearing in Port-au-Prince, defence attorney Edwin Coq told reporters he would ask the judge to grant the detainees "provisional release," a type of bail that doesn't require posting money.

Coq said the missionaries should be allowed to leave Haiti until their trial, a date for which has not been set.

"I hope that they will be released today," said Coq, who argued on behalf of his clients one by one. Late in the day, the 10 Americans were pushed into a waiting police van outside the courthouse and driven away.

The investigating judge charged them on Thursday with kidnapping for trying to take 33 children across the border into the Dominican Republic on Jan. 29 without documentation.

Laura Silsby, one of 10 American missionaries accused of illegally trying to take children out of Haiti, is escorted by Haitian police in Port-au-Prince on Wednesday. (Eduardo Munoz/Reuters)

Coq has said that the group's leader, Laura Silsby, knew she couldn't remove the youngsters without proper paperwork, but he characterized the other nine missionaries as unknowingly being caught up in actions they didn't understand.

"They were naive," he said. "They had no idea what was going on and they did not know that they needed official papers to cross the border. But Silsby did."

The missionaries' detention has raised concerns in other countries, including France, whose Foreign Ministry on Friday urged the Haiti to quickly set up a bilateral commission to look into adoption procedures. French families have taken in 277 Haitian children since the earthquake on Jan. 12.

Family members of the detained Americans released a statement late Thursday saying they were concerned about their relatives jailed in a foreign country.

"Obviously, we do not know details about what happened and didn't happen on this mission," the statement said. "However, we are absolutely convinced that those who were recruited to join this mission travelled to Haiti to help, not hurt, these children."

'Orphans' had parents

Most members of the Baptist group are from two Idaho churches. They said they were rescuing abandoned children and orphans from a country that UNICEF says had 380,000 youngsters in that situation even before the quake.

But at least two-thirds of the children involved in the case, ranging in age from two to 12, have parents, although the parents of some told The Associated Press they gave their children up willingly because the missionaries promised them a better life.

Each American was charged with one count of kidnapping, which carries a sentence of five to 15 years in prison, and one of criminal association, punishable by three to nine years. Coq said the case would be assigned a judge and a verdict could take three months.

"Obviously, this is a matter for the Haitian judicial system," U.S. Secretary of State Hillary Rodham Clinton said Friday.

Clinton's husband, former U.S. President Bill Clinton, now a special U.N. envoy for Haiti relief, met with President Rene Preval in Port-au-Prince on Friday but said his visit had nothing to do with the detained Americans. He said, however, that Washington was monitoring their welfare.

Three national leaders of the Southern Baptist Convention sent a letter Friday to President Barack Obama, urging him to "do everything within the authority of your office to secure a safe return home" for the detainees.

The leaders added that they could not "speak authoritatively about the motives and actions" of those detained, saying they went to Haiti on their own and weren't part of the Southern Baptist Convention's international relief efforts.

Silsby wanted to create an orphanage for Haitian children in the neighbouring Dominican Republic. She and the other nine went to Haiti after the earthquake to gather children for their project.

Most of the children were from the village of Callebas, where parents said they handed the kids over because they couldn't feed or clothe them. Their stories contradicted Silsby's account that the children came from collapsed orphanages or were handed over by distant relatives.

Silsby also said she believed she had all the necessary documents to take the children. The Dominican consul in Haiti, however, said he warned Silsby her mission would be considered child trafficking if she lacked adoption papers signed by Haitian officials.