NEW DELHI — India has executed the sole surviving Pakistani gunman who participated in the 2008 terror attacks in Mumbai. The execution came days before the fourth anniversary of the attack, which killed 166 people and has been described as India’s worst-ever terror strike.

The execution of Pakistani militant Mohammad Ajmal Kasab was a swift and secret operation. It was announced by Home Minister Sushil Kumar Shinde early Wednesday.

“This morning at 7:30 Ajmal Kasab was hanged in Yerwada Central prison, Pune in Maharashtra,” announced Shinde. “Doctors have issued certificate of his death.”

Shinde says the execution was a tribute to all innocent victims and police officers who lost their lives in the November 2008 Mumbai terror attacks.

He was buried in the jail compound where he was hanged in Pune.

The execution was carried out two weeks after President Pranab Mukherjee turned down Kasab’s mercy petition. He was sentenced about two years ago for waging war against India, murder and terrorism.

Kasab’s trial and hanging was fast-tracked in India, where the judicial process is usually very slow and where prisoners often languish on death row for years.

The 25-year-old gunman was among ten militants who went on a 60-hour rampage in Mumbai with grenades and automatic weapons, attacking multiple targets including two five-star hotels, a Jewish Center and a rail station.

Indian Foreign Minister Salman Khurshid says Pakistan was informed that the execution was to take place, but Islamabad apparently ignored the information.

“We attempted to convey to Pakistan foreign office that this decision had been taken and the execution will be done this morning,” said Khurshid. “Since those missives were not accepted by foreign office, by fax we indicated the information to them. Therefore, our obligation to inform them adequately was fulfilled.”

Kasab had initially pleaded not guilty, but later confessed to his involvement in India’s worst-ever terror strike. CCTV footage of Kasab, armed with an automatic weapon at Mumbai’s rail station, became the enduring image of the Mumbai attacks.New Delhi blames the attack on the Pakistan-based Islamic militant group, the Lashkar-e-Taliban (LeT). And, Islamabad has said the attack was partly planned on its soil.

New Delhi has blamed Pakistan for not doing enough to prosecute the main plotters of the attack, including Lashkar-e-Taliban founder Hafiz Saeed.

In Pakistan, authorities are trying seven suspects accused of playing a role in the attacks. They include Zaki ur Rehman Lakhvi, who is allegedly a commander of the LeT and a key planner of the assaults.

His lawyer, Khawaja Harris Ahmed says that Ajmal Kasab’s execution has weakened the prosecution’s case against his client, because Kasab is now unable to testify. He says the execution also undermines the use of Kasab’s confession in a Pakistani court.

“If there was any possibility of this (Kasab’s confessional) statement having any impact on the trial in terms of approving the prosecution’s case, now they have made sure that, that will never take place,” he said. “His statement could, and it could actually under certain circumstances, be used by his appearing as a witness rather his being part of the co-accused, even that possibility is now excluded.”

In Mumbai, which was devastated by the attacks, the execution was welcomed. However, many people said there would be no closure for them until the masterminds of the attacks were also brought to justice.

Relations between India and Pakistan plunged after the attacks, but have improved in the past year. Analysts say Kasab’s hanging is unlikely to impact warming ties.