President-elect Pranab Mukherjee Monday said he could not comment on the clemency plea of 2001 parliament attack convict Afzal Guru till he assumed office and studied the issue.

"I can't comment on Afzal Guru until I have assumed office and gone through the issue," Mukherjee told CNN-IBN in an interview, a day after he was elected India's 13th president with an overwhelming majority of parliament members and legislators voting for him across the political spectrum.

It is one of the hottest issues awaiting his decision.

The comment came as the Shiv Sena, which supported his candidature, demanded that Mukherjee reject the mercy petition filed by Guru.

"We have many expectations from you. We urge you to reject Afzal Guru's mercy plea and hang him. Pranabda, you should do this on priority basis and should kick-start your career as president of India. It is an august conduct that we expect from you," Shiv Sena chief Bal Thackeray said in his latest edition of party mouthpiece Saamna.

The president-elect, who has held key ministerial portfolios of finance, defence and external affairs in an eventful four-decade political career, was backed not just by partners of the ruling Congress-led United Progressive Alliance (UPA) but also by the Janata Dal-United (JD-U) and Shiv Sena, which broke ranks with the opposition alliance.

And this is what he said moved him.

"I'm particularly happy that those who committed, particularly those who don't belong to our party scrupulously adhered to their commitment and voted for me. That doesn't normally happen. I consider this a great reward to my long stay in public life."

Mukherjee, one of India's most experienced and canny politicians, also said animosity between political parties had left him disturbed.

"The hatred between political parties bothers me," he said.

Assuring that he would be a non-political president, Mukherjee said he would work for "everybody".

"It has been a long way from Mirati to Raisina. I was a very naughty child. I always got into trouble," he told CNN-IBN.

Mukherjee will taken oath Wednesday before assuming the office of president of India and moving into Rashtrapati Bhavan.