Janardhan Dwivedi declined to specify what the surgery was for, but told reporters it had been successful and that Gandhi would be absent for several weeks to recuperate.

"On the advice of her doctors, she travelled abroad and she is likely to be away for two to three weeks," Dwivedi said.

"We have just got information that the surgery was successful and her condition is satisfactory," he added.

Dwivedi said that in her absence, Gandhi had appointed a four-member group to handle the day-to-day running of the Congress Party -- including her son Rahul Gandhi who is tipped as a future prime minister.

Italian-born Sonia Gandhi is the widow of assassinated former premier Rajiv Gandhi and widely seen as India's most powerful politician, with her key power-broking position as Congress Party president.

Copyright AFP (Agence France-Presse), 2011