Chief of India's Congress Party Sonia Gandhi and her son MP Rahul Gandhi watch the ICC Cricket World Cup 2011 semi-final match between India and Pakistan in Mohali in this March 30, 2011 file photo. [Photo/Agencies]

NEW DELHI - The illness of Sonia Gandhi, India's most powerful political leader, may have set off a risky succession that could propel her inexperienced son Rahul to government just as the ruling Congress party battles corruption scandals and high inflation.

The appointment of the 41-year-old Rahul to a quartet that will administer political affairs for Congress as she is being treated for an undisclosed illness abroad came as a surprise to many - other more senior and experienced leaders were ignored.

Sonia Gandhi's illness was not disclosed in Thursday's surprise announcement, but the 64-year-old party chief may be away for weeks. Her absence may be longer if two newspaper reports, which said she had cancer, are correct.

The Congress party said on Friday she had undergone successful surgery - but Rahul's appointment may signal his rise to power ahead of the 2014 general election even is she quickly returns to office. ?

"Sonia Gandhi gives Congress keys to Rahul" was the headline of the Indian Express newspaper.

Stung by opposition criticism that India could not be run by an Italian-born figure, Sonia Gandhi nominated Manmohan Singh as prime minister after her 2004 election win. Since then she has largely run the country from behind the scenes, winning re-election for her party in 2009.

Rahul will now take these reins just as a raucous parliament debates some key reforms such as a land acquisition bill and battles accusations it turned a blind eye to a huge telecoms scam that has already seen a minister quit.

Rahul Gandhi, a lawmaker and the son of India's ruling Congress party chief Sonia Gandhi, watches the ICC Cricket World Cup semi-final match between India and Pakistan in Mohali in this March 30, 2011 file photo. [Photo/Agencies]