MUMBAI - The trial of the only Islamist militant suspect captured by police during the Mumbai attacks begins under heavy security in a specially reinforced courtroom.

Mohammed Ajmal Amir Iman, also known as Kasab, has not been seen in public since his arrest on November 26 last year, soon after 10 gunmen began an assault that left more than 160 people dead and over 300 others injured.

The 21-year-old Pakistani national, said to belong to the banned Pakistan-based Islamist group Lashkar-e-Taiba (LeT), faces a string of charges including "waging war" on India, murder, attempted murder and kidnapping.

The courtroom, last used to try suspects over the deadly 1993 bomb blasts in the city, has been reinforced, while a bomb-proof tunnel has reportedly been built from Iman's cell after he received death threats.

Traffic will be banned from around the prison for the duration of the trial, which is estimated to last up to six months and may hear testimony from as many as 2,000 witnesses.

The defendant, the nine dead gunmen and 35 other LeT "terrorists" wanted over the attacks carried out a "heinous criminal conspiracy" against the city and people of Mumbai and India, according to the chargesheet.

"This was with the express intention to destabilise India, wage war against the country, terrorise its citizens, create financial loss and issue a warning to other countries," it added.

Two other men are also on trial. Indian nationals Fahim Ansari, 35, and Sabauddin Ahmed, 24, are accused of providing the group with logistical support before the attacks.

Prosecutors say they have evidence that "undoubtedly and conclusively" links the attacks to India's arch-rival Pakistan, including mobile and satellite phone communication between the gunmen and their LeT "handlers."

Iman's DNA and fingerprints were found on items retrieved from the hijacked Indian fishing trawler the gunmen used to get to the Mumbai coast, it is alleged.

There is CCTV and other footage of him at Mumbai's main railway station, where more than 50 people died after two gunmen opened fire with AK-47 assault rifles and threw grenades.

Thirty eyewitnesses also picked him out in identification parades, it added.

The trial is taking place at Mumbai's Arthur Road jail before a single judge without a jury because of security fears. All pre-trial hearings have been held either behind closed doors or via video link.

Iman's state-appointed lawyer, Anjali Waghmare, was denounced for taking on the case and attacked by irate Hindu radicals.

She has since been given the highest level of police protection