Sonia Gandhi, leader of India's ruling Congress party, returned home yesterday after more than a month of medical treatment in the United States which had left the government rudderless to deal with the biggest protests in decades.

The absence of the powerful 64-year-old, who runs the country from behind the scenes, has caused serious problems for the coalition government, accused of mishandling the anti-corruption protests and facing challenges from the opposition that have frequency halted parliament proceedings.

"She came back this morning and she is fine," Congress party spokesman Janardan Dwivedi told Reuters.

Her illness added to an already long list of problems besieging Prime Minister Manmohan Singh, who has fallen behind schedule with a reform agenda he himself considers vital to bringing India's economic growth closer to double-digits.

Congress party officials hope her return will lift morale in the centre-left party, but analysts point out that her

absence did not affect day-to-day running of India.

The recent protests led by 74-year-old activist Hazare forced the prime minister to back down and agree to tougher anti-corruption legislation.

Concern remains whether the Italian-born Gandhi will be well enough to take the reins of her divided party and a drifting coalition government sagging in opinion polls.

Broadcaster CNN-IBN, citing party sources, said she may need another month to recover.

The Congress party has declined to comment on the nature of her illness. But several media outlets have said she

was treated for cancer at the Sloan-Kettering Cancer Centre in New York.

After leaving for surgery, Gandhi promoted her politically inexperienced son Rahul to help manage the party in her absence. He is widely expected to be the next prime minister if the Congress party returns to power in2014 elections.

Rahul was sharply criticised for his handling of the protests in August, largely remaining out of view and not convening any meetings with the officials Sonia had appointed, along with him, to run her affairs in her absence.

The government was also sharply criticised for failing to head off a bomb attack at the capital's High Court yesterday which killed 12 people. The court has no CCTV cameras and handheld scanners were not working on the day of the attack.

Rahul and Prime Minister Singh were heckled when they visited blast victims at a Delhi hospital.

Recent opinion polls show support for the centre-left Congress party sharply falling behind the opposition Hindu nationalist Bharatiya Janata Party.