India's Supreme Court has upheld the death sentence for the lone surviving gunman among a group of militants who killed 166 people in the 2008 Mumbai attacks.

The ruling Wednesday leaves Mohammed Ajmal Kasab, a Pakistani national, with a final option to appeal to India's president for clemency.

A Mumbai court convicted Kasab in 2010 on charges of murder, terrorism and waging war against India, but he says he was denied a fair trial.

He initially pleaded not guilty, but later confessed his involvement in the three-day siege.

Kasab and nine other young, heavily-armed Pakistanis attacked luxury hotels, a Jewish center and a busy train station in India's financial capital.

India has blamed the Pakistan-based militant group Lashkar-e-Taiba for the siege. It claims the attacks were carried out with state support from Pakistan — a charge Islamabad denies.