A US couple accused of murdering their eight-year-old daughter say they feel "kidnapped" by the Gulf emirate, with no verdict expected in their case until late March.

Matthew and Grace Huang, Americans of Asian origin, were arrested in January 2013 after the death of their adopted daughter Gloria, an eight-year-old girl from Ghana, and accused of causing her death in order to sell her organs.

The couple were released in November pending trial, but on Wednesday the court denied their request to leave the country to join their other two adopted children in the US, and said a verdict would be announced March 27, according to a judicial source.

The defence said the public prosecutor is pushing for the death penalty, although there has been an effective moratorium on executions for several years, the AFP news agency reported.

The couple's supporters describe them as a loving family and say the girl died of an eating disorder caused by the "extreme poverty" she suffered at a young age in the West African country.

"We have lost our daughter and our sons have lost their sister. And this court has taken more than a year of our lives," Matthew Huang said outside the courtroom.

"In the midst of our innocence, we feel we have been kidnapped and we just want to go home."

Supporting testimony

Both adoption and multiracial families are rare in Qatar and the family's supporters maintain that authorities misunderstood the Huangs' situation and found it inherently suspicious.

The "Free Matt and Grace" website said police accuse the couple of having adopted the children "in order to harvest their organs, or perhaps to perform medical experiments on them".

The family's supporters describe them as a loving family, and say they have collected supporting testimony from people who knew them in Qatar, which authorities have declined to accept.

The Huangs moved to Qatar in 2012 so Matthew, an engineer, could work on infrastructure projects related to the 2022 World Cup.

Source: Agencies