Polo player Shivraj Singh, hospitalised here after an accident in Jaipur a week ago, remained in critical condition Thursday, two days after neurosurgeons operated on him.

Doctors at the Bombay Hospital where he has been admitted said Shivraj Singh, the only son of former Jodhpur maharaja Gaj Singh, was still in coma although he was showing some signs of improvement.

"Shivraj Singh is still not out of danger," a hospital source said.

Doctors said although the swelling in his brain had come down, he continued to be in a serious condition. Doctors are waiting for the 29-year-old ace player to come out of coma.

Shivraj Singh was brought to Mumbai from Jaipur Tuesday and admitted to the Bombay Hospital. Doctors then performed a two-and-a-half-hour operation on him.

The Britain-educated Shivraj Singh was thrown off his horse while trying to turn the moving animal just minutes after the start of the match at the Rambagh polo ground Feb 18.

After 48 hours of observation and studying his MRI report, doctors in Jaipur decided to move him to Mumbai.

"He has suffered injuries on the left side of the brain which has caused the swelling," a doctor said, adding that it could take around 20 more days for it to subside.

Shivraj Sing0h had suffered a similar polo accident two years ago in Jodhpur.