"What about Afzal Guru, who attacked Parliament, our temple of democracy, in 2001? That offence predates Kasab's heinous act by many years," Modi tweeted.
Kasab, the lone surviving terrorist of the 26/11 attack, was hanged at the Yerawada Jail in Pune at 7.30 am on Wednesday.
Guru, whose mercy petition is pending with the President was sentenced to death much before in 2004.
The home ministry had recommended in August 2011, to then President Pratibha Patil that Guru, who has remained a death row prisoner in the Tihar Jail for the past seven years be swiftly executed. But the issue has been pending for years and has been a subject matter of intense political controversy.
Guru was convicted for conspiracy in the December 2001 Parliament attack and the order of his death penalty was upheld by the Supreme Court in 2004. The sentence was scheduled to be carried out on October 20, 2006. However, Guru’s execution was stayed following a mercy plea filed by his wife.