Human rights watchdog Amnesty International has urged India to halt further executions, less than a month after Pakistani militant Mohammed Ajmal Amir Kasab was hanged for his role in the Mumbai terror attacks.

According to Indian government figures, there are currently 477 convicts on death row, including 2001 parliament attack main conspirator Afzal Guru.

In a letter to Indian President Pranab Mukherjee, Amnesty India has appealed to him to commute all death sentences to life in jail. "(We) urge the Indian authorities to immediately establish a moratorium on executions with a view to abolishing the death penalty," Amnesty said.

The human rights watchdog also slammed the secretive manner in which Kasab was executed on November 21.

"Information about the rejection of the petition for mercy and the date of execution was not made available to the public until after the execution had been carried out... in contrast to how previous executions have been carried out in India over the past 15 years," Amnesty said.

India rarely executes prisoners on death row.

Kasab was the second person to be executed since 1995. In 2004, a man convicted of raping and killing a schoolgirl was hanged in the eastern city of Kolkata after then Indian President Abdul Kalam rejected his clemency plea.