On the day the attacks started, Mr. Kasab said, police took him from his cell because he resembled one of the gunmen, shot him to make it look like he had been involved in the violence and re-arrested him.
Friday's statement was not the first reversal from Mr. Kasab.
In February, he told a judge he wanted to attack India in order to free the divided region of Kashmir where Muslim militants are fighting for independence. He later recanted that statement, saying it was obtained under duress.
It was unclear what impact Mr. Kasab's statement would have on the case, and the prosecution brushed it off.
"All the while, I expected that Mr. Kasab was about to take a U-turn in the case," said Ujjwal Nikam, the prosecutor. "He is a military-trained commando. It's not going to affect our case."
In July, Mr. Kasab, who could face the death penalty if convicted, surprised the court when he suddenly confessed, saying he would rather be hanged in this world than face "God's punishment" in the next.
In his confession, he spoke of spraying gunfire into the crowd at the train station and described in detail a network of training camps and safe houses across Pakistan, revealing the names of four men he said were his handlers.
The photo of Kasab casually walking through the station with his rifle has become the enduring image of the attacks.
But Kasab said police tortured him into falsely confessing.
The assault 13 months ago lasted nearly three days and paralyzed India's commercial hub. During the attacks, 10 young men armed with assault rifles stormed two luxury hotels, a Jewish center and the train station. Nine of the gunmen were killed, leaving only Mr. Kasab, who was wounded in a shootout with police, authorities said.
He told the court Friday he was initially arrested last year after wandering around Mumbai late at night looking for a place to stay, and his Pakistani citizenship aroused suspicion.
After he was re-arrested for the Mumbai attack, he said, four white men came to visit him in jail, including David Coleman Headley, who is jailed in Chicago on charges he conspired in the siege. The judge then told Mr. Kasab not to reveal any more details on Headley.
Mr. Headley, the 49-year-old son of an American mother and Pakistani father, is also charged with planning to attack a Danish newspaper.