SHANGHAI -?Doctors in a Shanghai hospital successfully separated twin girls joined at breast and abdomen after nearly six hours of surgery on Monday, and both girls are in a stable condition.

The twin girls, named "An An" and "Xin Xin", were born in late April this year, with their livers and heart-sac connected, according to Liu Jinfen, director of Shanghai Children's Medical Center, where the surgery was conducted.

The operation started at 9 am and four groups of doctors operated at the same time. "We separated their hearts and livers, reshaped their ? breast bones and remodeled their breasts with titanium-alloy plates," Liu said after the operation.

The conjoined twin girls were transferred to ICU in Shanghai Children's Medical Center two hours after their birth at 4.89 kg.

After four months of comprehensive nursing, the twin girls, at 10 kg, were ready for the operation, Liu said.

"The operation is challenging, but we made it," Liu said, adding that further intensive care and treatment is crucial for the girls' health.

The two girls might rely on breathing machine for a long time, Liu said.