Al Jazeera's Jonah Hull, reporting from the capital Port-au-Prince, said the investigative judge would review the evidence himself and make a decision as to whether the 10 go to trial or be set free.

The judge could take three months to decide, our correspondent said, and the Americans could face sentences of up to 15 years in prison.

The 10 Americans were arrested last week on Haiti's border with the Dominican Republic when they tried to cross with the busload of children they said were orphaned by the devastating January 12 quake.

Haitian authorities said the group lacked the authorisation needed to take the children out of Haiti.

After the Americans' arrest, evidence emerged that most of the children intercepted with them were not orphans.

Haitian police said some parents admitted to handing over their children to the church group in the belief the children would get an education and a better life.

'Let us help'

All 10 Americans, who ranged in age from 18 to 55, acknowledged under questioning from the prosecutor on Thursday that they had apparently committed a crime by seeking to take the children across the border without proper documents.

special report
Special Report: Haiti earthquake

But they said they were unaware of that until after their arrest.

"We didn't know what we were doing was illegal. We did not have any intention to violate the law. But now we understand it's a crime," said Paul Robert Thompson, a pastor who led the group in prayer during a break in the session.

Laura Silsby, the group's spokeswoman, told the hearing: "We simply wanted to help the children. We petition the court not only for our freedom but also for our ability to continue to help."

She said her group was taking the children to a 45-room hotel it was converting to an orphanage in Cabarete in the Dominican Republic.

"We were going to house them there," she said of the beach resort. "They could stay there, go to school and live well and the parents could come and visit them."

The Americans, who have been in jail since last Friday, did not speak to a mob of reporters as they were taken back to police headquarters to await the judge's decision.

Sensitive case

The case could be diplomatically sensitive at a time when the US is leading a huge relief effort to help hundreds of thousands of Haitian quake victims, and as US aid groups pour millions of dollars of donations into Haiti.

Haiti has tightened adoption procedures since the quake [GALLO/GETTY]

The US state department has been at pains to avoid any impression it might be interfering in the matter.

Hillary Clinton, the US secretary of state, had on Wednesday said for the first time that Washington was "engaged in a discussion with the Haitian government about the appropriate disposition of their cases".

But PJ Crowley, a spokesman for the state department, on Thursday sought to play down Clinton's comments, saying: "I wouldn't read too much into that.

"I would put this in the context of asking for clarifications about ... what [Haitian judicial officials'] procedure would be … timeline, capacity to be able to pursue this case."

Clinton had also said on Wednesday that "it was unfortunate that, whatever the motivation, this group of Americans took matters into their own hands".

Haiti's overwhelmed government has tightened adoption procedures since the quake, saying it feared traffickers could try to take advantage of the disaster by spiriting away vulnerable children.

The authorisation of Jean-Max Bellerive, the prime minister, is now required for any child to be taken out of the country for adoption.

And Bellerive said the Americans' case was stealing attention from the plight of Haitians.

"I believe it's a distraction for the Haitian people because they are talking more now about 10 people than they are about one million people suffering in the streets," he said.