New Delhi, Aug 4 (IANS): Congress president Sonia Gandhi has successfully undergone surgery abroad and is not likely to attend parliament for the next two-three weeks, a senior party leader said here Thursday.

Congress general secretary Janardhan Dwivedi, who did not name the country where Gandhi underwent surgery, said she had formed a group comprising four party leaders, including son Rahul Gandhi, to look after matters related to the Congress in her absence.

"Sonia Gandhi has been recently diagnosed with a medical condition that requires surgery. On advice from her doctors, she has travelled abroad and is likely to be away for two to three weeks," Dwivedi said here.

Congress sources said she is undergoing treatment in the US, but refused to name the nature of illness.

Dwivedi said party leaders received news Thursday that the surgery has been successful.

He said Sonia Gandhi also sent a communication forming a group to look after the Congress party matters.

"In my absence, a group consisting of the following will look after matters relating to Congress party - A.K. Antony, Rahul Gandhi, Janardan Dwivedi and Ahmed Patel," Dwivedi quoted from Gandhi's communication.