Prime Minister Manmohan Singh on Saturday underwent a surgery to treat benign enlargement of the prostrate gland at the All India Institute of Medical Sciences. The surgery was performed by a team of doctors led by Professor N P Gupta, head of the Department of Urology at AIIMS. Dr Singh, 75, was admitted to AIIMS at 6 am and the surgery lasted till 9 am. The prime minister will rest for the next two days at AIIMS and return home by Monday morning.