NEW YORK • A pair of identical twins from China who were separated at birth and adopted by two different families in the United States have been reunited for the first time.

The identical 10-year-olds, Audrey Doering and Gracie Rainsberry, embraced each other and cried as they met for the first time on ABC's daytime show Good Morning America on Wednesday.

The twins had grown up hundreds of kilometres away from each other after being adopted shortly after birth by two different families - Audrey in Wausau, Wisconsin, and Gracie in Richland, Washington.

Neither of their families knew that the girls had a sibling until December, when Audrey's mother found a photo of both of them together as babies, posing with their Chinese foster mum.

Ms Jennifer Doering became curious about her daughter's past while she was trying to find a Christmas present for her.

She wanted to give her daughter a copy of her "finding ad" - a photo that gets published in Chinese newspapers when a baby is placed in an orphanage.

Through a Chinese researcher, she discovered a photo that showed her daughter on the knee of her Chinese foster mother, who was carrying another baby that looked just like Audrey. "As soon as I had that picture, I was desperate to find out... who that other child was," Ms Doering said, according to an ABC News report.

She found out that the other child was her daughter's twin, who had also been adopted and taken to the US. "Oh, it was unbelievable. I was like, 'How?' I mean, this is stuff you read about," Ms Doering said. "And how, how could it really be that there are two of them?"

With the help of Facebook, Ms Doering was able to find Ms Nicole Rainsberry, Gracie's mother, said ABC News. Ms Rainsberry said that finding out about her daughter's twin was "surreal".

The families also discovered that the twins both suffered from heart conditions. Gracie underwent two heart operations after arriving in the US and Audrey underwent one, their families told the show.

When Audrey heard the news that she had a twin, she said: "I thought my parents were playing a joke on me."

Gracie said she was overwhelmed with emotion and cried a lot when she found out she had a twin, reported ABC News. After their live TV meeting, Gracie said she was excited and happy.

Audrey said: "It felt like there was somebody missing. Now, it's complete."