Ghanaian authorities detained an American couple on suspicion of trying to adopt four children illegally in the African nation, U.S. officials said.

Soheil and Christine Moghadam from Irvine, California, traveled to Ghana with their two biological children to adopt four siblings there.

They adopted the children on June 14, but officials in the nation questioned the legality of their adoption, leading to their detention over the weekend, according to Victoria Nuland, a spokeswoman for the State Department.

"Ghana was concerned that some of the documents they had weren't filled out properly or were forged," said Hank Fortener, founder of AdoptTogether, an advocacy group that provides a platform for prospective parents to raise funds. The couple used the group's website to raise funds.

African adoption should be discouraged 'at all costs,' group says

Though they are still in the nation, Ghanaian officials have since determined their documents are legitimate, according to Fortener.

A bond has been posted for their release and they were reunited with their biological children Monday, Nuland said this week.

"We are emotionally exhausted and traumatized from the entire incident but we are thankful to have support and prayers from friends and family worldwide," the Moghadams said on their blog, Our adoption journey to Africa.

"Our case is not complete yet, but our chief officer from the Ghana police department has apologized for their overreaction and stated that our detainment was a mistake on their part. "

CNN's repeated attempts to reach the couple and Ghanaian officials were unsuccessful.

The Moghadams initially planned to adopt a child in Ethiopia in 2010, but decided on Ghana after they saw the four siblings on the waiting list of an adoption agency.

Africa has seen a surge of adoptions in the past eight years, according to adoption expert Peter Selman from Newcastle University in Britain.

A new report from The African Child Policy Forum entitled "Africa: The New Frontier for Intercountry Adoption" says prospective adoptive parents are turning "en masse" to the continent as other countries toughen their laws.

Most children adopted from Africa go to the United States or France, two of the world's biggest receiving countries, Selman said.