The lone surviving gunman from the 2008 Mumbai attacks that left 166 dead has approached the Indian Supreme Court asking for his death sentence to be overturned, a court source told AFP Friday. The source said the request by Mohammed Ajmal Amir Kasab had been filed via jail authorities in Mumbai, where he has been held since the attacks, and lodged with the secretary general of the court. \"He filed the appeal through the Arthur Road jail authorities,\" the source said, asking not to be named. Pakistani national Kasab, one of 10 Islamist gunmen who laid siege to the city for nearly three days, was first convicted and sentenced by a trial court in the Indian commercial and entertainment capital in May 2010. The death sentence was confirmed by the state high court in February in the first failed appeal by the 23-year-old school drop-out from a poor farming area in Pakistan\'s Punjab state. India has the death sentence for the \"rarest of the rare\" criminal offences and executions are uncommon. Kasab was found guilty of a string of offences including waging war against India, murder, attempted murder and terrorist acts after a trial at a maximum security prison court in Mumbai. During the trial, the prosecution produced fingerprint, DNA, eye-witness, CCTV and other evidence showing him opening fire and throwing grenades in the bloodiest episode of the November 26 attacks at Mumbai\'s main railway station. A number of senior police officers, including the head of the Maharashtra state anti-terrorism squad, were killed as the gunmen fled the scene of carnage. Three luxury hotels, a popular tourist restaurant and a Jewish centre were also targeted by the other gunmen. If the Supreme Court upholds the verdict and sentence, Kasab can appeal for clemency to India\'s president as a last resort. The last execution in India was in 2004, but in May India’s president unexpectedly rejected a mercy petition from a murderer in the northeastern state of Assam. The state faces a difficult search for a hangman, however, because the small number of known candidates have either died or retired. India has accused the banned, Pakistan-based Islamist group Lashkar-e-Taiba of being behind the attacks, which led to the suspension of fragile peace talks between the two neighbours and rivals.