There are mounting concerns in Haiti's earthquake-hit capital over the welfare of thousands of orphans suffering amid the devastation.

Al Jazeera has learnt of at least one government-sanctioned orphanage in the capital, Port-au-Prince, where children are kept in shocking conditions.

In at least one case a child was tied down.

The plight of orphaned children in Haiti has led to calls for international adoption processes to be sped up, but fears over human trafficking have complicated the process.

Americans detained

Over the weekend two Americans, who were escorting six Haitian orphans to the US, were briefly detained when authorities at Port-au-Prince's airport were suspicious about their documents.

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After several hours, an official from the US embassy arrived with paperwork that allowed them to be freed, the Associated Press reported.

Lucia Newman, Al Jazeera's correspondent, reporting from Port-au-Prince, said: "These women had the papers to take some eight children to the United States for adoption, but the authorities believed - at least at one point - that they had falsified the documents and arrested them.

"Now this incident has been cleared up.

"All of this highlights that there is a tremendous amount of interest worldwide in trying to help Haitian orphans, but there's also an equally great amount of concern that these children not fall into the wrong hands."

Large numbers of children have been left vulnerable by the 7.0-magnitude earthquake, which struck on January 12 and killed, at the most recent estimate, about 300,000 people.

Elsewhere in the capital, homeless earthquake victims said police were halting deliveries of food and water to try to force them to leave their camp on the grounds of the prime minister's office.

Witnesses also claimed police beat a 22-year-old woman at the camp after she picked up a broom to sweep around her tent. She was later taken to hospital.