London, England (CNN) -- Surgeons in London successfully separated four-month-old conjoined twins after a 14-hour operation Thursday, the hospital announced.
Hassan and Hussein Benhaffaf, who were joined at the chest, are in intensive care and sedated but stable, said consultant pediatric surgeon Edward Kiely, of Great Ormond Street Hospital.
"We are pleased with how the operation went," Kiely said.
The hospital said the next few days would be very important for the twins, whose family live in Ireland.
The twins were born in December at University College London Hospital, CNN affiliate ITN reported. Though joined at the chest, they shared no major organs, Britain's Press Association and Irish broadcaster RTE reported.
Their parents, Angie and Azzedine Benhaffaf, flew with their babies to London last month to prepare for the operation, ITN reported.
"The sun is shining today for our two little fighters, who have won the battle of their lives!" the parents said in a written statement. "Words cannot express the relief and love we feel for our two boys.
"We thank God, we thank the surgeons and the gifted team at Great Ormond Street Hospital, and we thank from the bottom of our hearts the Irish nation and everyone who prayed for our beloved twins.
"We are so proud of the courage and strength that Hassan and Hussein have shown, and they both have made the world a much better place with them in it."
Great Ormond Street Hospital is known for its specialist pediatric care. In conjunction with the University College London Institute of Child Health, it operates what it says is the largest center for pediatric research outside the United States.