India has executed convicted bomb plotter Yakub Memon for his role in a series of co-ordinated attacks that killed hundreds of people in Mumbai in 1993, local media say.

Memon was hanged at Nagpur jail in the western state of Maharashtra in the early hours of Thursday, according to the NDTV and CNN-IBN news channels.

Last-ditch pleas for clemency were rejected by President Pranab Mukherjee and the country's Supreme Court.

The Bombay Stock Exchange, the offices of Air India and a luxury hotel were among about a dozen targets of the March 1993 blasts, which killed 257 people in the deadliest attacks ever to hit India.

They were believed to have been staged by Mumbai's Muslim-dominated underworld in retaliation for anti-Muslim violence that had killed more than 1,000 people.

Memon, a former accountant by profession, was the only one of 11 people convicted over the atrocity to have his death sentence upheld on appeal. The sentences on the others were commuted to life imprisonment.

He has denied any involvement in the blasts during a staggered trial and appeal process that has bitterly divided opinion in India, and led to calls from rights activists and an ex-judge for his life to be spared.

Former Supreme Court judge Harjit Singh Bedi had said the Supreme Court should take notice of reports that Memon had co-operated with investigators and returned voluntarily from Pakistan, where he fled after the blasts.

Others pointed out that his brother Tiger Memon was alleged to have masterminded the attacks, along with Mumbai gang boss Dawood Ibrahim. Both have been on the run since 1993.

Executions are only rarely carried out in India, but President Pranab Mukherjee has rejected a number of mercy pleas in the past three years, ending a de facto eight-year moratorium.

Amnesty India said before Yakub's execution it was disappointed by the decision to go ahead with the hangings.

"The judgement regrettably puts India in opposition to the global trend towards moving away from the death penalty," the human rights group said.