Union HRD Minister and senior Congress leader Arjun Singh was on Wednesday admitted to AIIMS after he complained of severe pain in the abdomen. Earlier, he was admitted to LNJP Hospital. He was later referred to AIIMS where doctors treating him said though the minister's vital organs functioned normally, he would have to be closely monitored for a few days.Singh, who has a medical history of diabetes and hypertension, on Wednesday was diagnosed with 'acute cholecystitis' (stones in the gall bladder accompanied with severe infection) and 'sepsis syndrome' (blood infection) at the LNJP Hospital. "He had high fever when he arrived at the hospital and was complaining of acute pain in his abdomen," said a source at the hospital.Examined by a team of doctors, including gastroenterologists and nephrologists, he was referred to AIIMS for critical care monitoring. "His condition was quite critical and that's why it was necessary to refer him to AIIMS," added the source.The minister was accompanied by his daughter and personal physician.The doctors at AIIMS say he will require at least a week to 10 days to get back to his daily routine.