India on Wednesday executed Mohammed Ajmal Amir Kasab, the only Pakistani militant caught alive in 2008 Mumbai terror attacks, in a top-secret operation in a high-security prison in the western city of Pune, just days before the fourth anniversary of the massacre.

"At 7.30 a.m. local time Ajmal Kasab was hanged in the Yerawada prison. Pakistan has been informed of the hanging. If there was a request for Kasab's body, we would have obliged, but there was no such request," Indian Home Minister Sushil Kumar Shinde told the media in the Indian capital.

In fact, 25-year-old Kasab was shifted to Pune's prison from the high-security Arthur Road jail in Mumbai two days ago, an operation which was kept under wraps till he was hanged this morning.

Justifying the secrecy of the operation, the Home Minister said: "The secrecy was necessary as it was a high-profile operation. This is a tribute to all innocent people and police officers who lost their lives in this heinous attack on our nation."

Kasab's hanging came weeks after Indian President Pranab Mukherjee rejected his clemency plea and at a time when Indian Prime Minister Manmohan Singh was out of the country -- he is on his way back to the national capital from Cambodia where he attended the ASEAN Summit.

Moreover, sources said that Pakistani Interior Minister Rehman Mallik's visit to India -- due to begin on November 22 -- was canceled at the last minute as India did not want to host a Pakistani delegation at the time of the execution which was decided soon after President rejected Kasab's mercy plea on November 5.

Kasab was sentenced to death in 2010 by a special Indian court after he was found guilty on 80 offences, including waging war against the state. His death sentence was upheld by the High Court in Mumbai. Kasab's appeal against the death sentence was rejected by the Supreme Court in August this year.

India's main opposition Bharatiya Janata Party (BJP) welcomed the hanging, saying it was "better late than never". "It is a warning for those trying to instigate terror attacks in India, as well as succor for those who have suffered due to these attacks," BJP Vice-President Mukhtar Abbas Naqvi told the media.

The last time such an execution took place was in 2004 in the eastern state of West Bengal's capital Kolkata where a man was hanged for raping and killing a schoolgirl.

Experts say that India's ruling Congress-led United Progressive Alliance government was under tremendous pressure to act against Kasab, who along with nine of his associates, carried out one of the deadliest attacks in the country, in which over 170 people were killed and more than 300 others injured.

"There has been an overwhelming demand among people in India since 2008 that Kasab be executed," said Prof Ajay Singh, a Delhi- based political expert.

He added: "Kasab's hanging was aimed at boosting the Indian government's image, perceived to be weak by many. The UPA government has been under fire for its inability to prevent corruption as well as inflation. This political move is a morale booster."