D S Rana, Chairman (Board of Management) of the hospital said that Gandhi, 70, is under observation.
"Sonia Gandhi was brought to the hospital at 5 PM today. She has been found to be suffering from stomach upset and has been admitted for observation," said Rana in a statement.
According to sources, Gandhi was rushed to the hospital in an air-ambulance from Shimla, where she had gone for a vacation.
A team of doctors from the hospital was deputed to bring her back from Shimla.
Party sources said her condition was stable.