Sri Lankan doctors performed emergency surgery Thursday to save a pregnant Covid-19 patient, delivering quadruplets who tested negative for the virus, a state-run hospital said.

The 25-year-old woman was rushed into a Caesarean-section surgery to deliver the babies prematurely as her condition deteriorated, the director at the De Soysa maternity hospital, Sagarika Kiriwandeniya, said.

"We had to deliver the babies before full term because the mother was developing complications," Kiriwandeniya told reporters in Colombo. "The mother and her four babies are in a stable condition but under intensive care," 

The hospital assembled a team of 35 medical staff, including 19 doctors, to perform the procedure on the woman, who was in her 32nd week of pregnancy.

A rapid antigen test showed that the babies -- two boys and two girls -- do not have Covid-19, Kiriwandeniya said, adding that the multiple births added new challenges because the mother had Covid-related complications.

The babies weighed between 1.1 kilograms (2.42 pounds) and 1.6 kilograms (3.52 pounds).

Virus infections have surged in Sri Lanka since October, when the number of cases increased more than tenfold to 35,387, with 160 deaths.