Sonia Gandhi leaves India to have surgery abroad
India's governing Congress party leader Sonia Gandhi is to have surgery abroad for an undisclosed medical condition.
Congress party spokesman Janardhan Dwivedi said Mrs Gandhi was "likely to be away for two to three weeks".
Earlier he said the surgery had already taken place and been successful, but he later corrected his statement.
Mrs Gandhi, 64, is seen as India's most powerful politician. She holds no official post, but many consider her the de facto head of the government.
The announcement has taken India by surprise. It is not clear where Mrs Gandhi has gone - the Press Trust of India, quoting Congress party sources, reports that she left for the US on Wednesday.
The BBC's Mark Dummett in Delhi says her absence comes at a critical time for the government as it deals with corruption scandals and high price rises.
India has some of the best medical facilities and doctors in the world and speculation is rife as to why Mrs Gandhi chose to go elsewhere for surgery.
Some reports suggest she may need specialist treatment not yet available in India, but these are unconfirmed.
Other people wonder whether Mrs Gandhi wants to avoid the inevitable media circus there would be, were she to attend a hospital in India.
Mr Dwivedi did not say what the operation was for, nor where it would take place.
"Sonia Gandhi has been recently diagnosed with a medical condition that requires surgery... She has travelled abroad and is likely to be away for two to three weeks," he told reporters.
Earlier the spokesman said that she had already had a successful operation in the US, but later corrected his mistake, saying it would take place in the next two to three days.
Mrs Gandhi has named a four-member team to run party affairs during her absence, he said. The team includes her son and MP Rahul Gandhi, who is tipped as a future prime minister.
Mrs Gandhi's absence from the opening session on Monday was remarked upon in the Indian media, but explained by a "viral infection" from which she was said to be suffering.
Italian-born Mrs Gandhi is the widow of former Indian prime minister Rajiv Gandhi. She nominated Manmohan Singh to the prime minister's post in 2004 and is widely believed to be more powerful than him.
The powerful Nehru-Gandhi dynasty has ruled India for most of the time since the country gained independence from British colonial rule in 1947.