Hackers broke into the Congress party website and replaced Sonia Gandhi's profile page with sexual innuendo, apparently timing the attack with the party president's 65th birthday on Friday.
It was not clear when the attack took place and Congress party leaders were not available for comment. The official website was inaccessible to the public at noon on Friday, a couple of hours after the hacked post was noticed on Gandhi's profile page.
The attack came just days after India urged social media networks including Facebook, Twitter and Google to remove offensive material from their websites, unleashing a storm of criticism from Internet users complaining of censorship.
A New York Times report Monday said Telecoms and Information Technology Minister Kapil Sibal called executives about six weeks ago and showed them a Facebook page that maligned Gandhi and told them it was unacceptable.
The government is very sensitive to criticism of Gandhi, whose family has dominated Indian politics for over six decades.