New Delhi: Congress President Sonia Gandhi will undergo a surgery in the United States for an undisclosed medical condition even as she constituted a four-member group comprising Rahul Gandhi to oversee its functioning in her absence that is likely to be for nearly a month.

Making a brief announcement, Congress General Secretary Janardhan Dwivedi, told reporters in Parliament House that the 64-year-old leader was recently diagnosed with a medical condition and was advised surgery.

"Smt Sonia Gandhi has been recently diagnosed with a medical condition that requires surgery. On the advice of doctors, she has travelled abroad and she is likely to be away for two-three weeks," he said.

Gandhi, accompanied by her son Rahul, had left earlier this week to an undisclosed destination in the US. Congress party was silent over when she left and where she was undergoing treatment.

Dwivedi had earlier said that Gandhi had undergone a successful surgery but clarified later that the operation would be carried out in a day or two.

He said Gandhi has decided that in her absence a group comprising Rahul Gandhi and senior leaders A K Antony, Ahmed Patel and Dwivedi will look after party affairs.

Significance is attached to the fact that Rahul will form part of the committee that has only one senior minister of the government and two leaders from the organisation.

Asked to explain the absence of Prime Minister Manmohan Singh and Finance Minister Pranab Mukherjee from the group, Congress spokesperson Manish Tiwari said "they (the Prime Minister and Finance Minister) are senior members who have been active in the organisation for long. To a question about her health condition and the kind of surgery, she has to undergo, Tiwari declined to go into details.

"Even public personalities are entitled to certain amount of privacy in so far as their medical condition is concerned. Our friends in media should bear that sensitivity in mind," he said.

While it was not immediately clear about the nature of medical problem, sources within the party said Gandhi had undergone a few tests over the past two days.

Ever since Dwivedi's announcement in the morning, there was speculation about the nature of her problem. In December, 2007, Gandhi was admitted for a week in the Ganga Ram Hospital where she was said to have been under treatment of an eminent gynecologist.

The sources said she had earlier also visited the US for medical examination and the surgery had been planned in advance.

The Congress President had been not keeping well in the past and because of her illness, she could not attend meetings of the Congress Core Group as also that of the Parliamentary Strategy Committee.