It is time for an introspection to ensure that "ghastly incidents" like the 1984 anti-Sikh riots never take place in the country, Prime Minister Manmohan Singh has said.

Intervening in a Rajya Sabha discussion on a censure motion on the Nanavati commission report on Thursday, he said the House was discussing an issue having grave implications for the country.

"4,000 people had been killed in 'the great national tragedy' in 1984. This was an occasion for introspection to ensure that such ghastly incidents never took place," he said.

1984 riots, a national shame: PM

Recalling the assassination of late Mrs Indira Gandhi, Singh said it was a "national tragedy." He, however, went on to add that whatever happened later was "equally shameful".

"I am not standing on any false prestige. I bow my head in shame," Singh said.

Pointing out that there were "ebbs and tides" in the affairs of a nation, the prime minister said, "though we cannot rewrite the past, we should have the ability to write a better future for all of us".

People should have every right to live a life of dignity, he added.

The prime minister said, "we are dealing with the past, present and future of our brave Sikh community, which has a glorious tradition, is part of the national mainstream and has contributed to the prosperity of Punjab."

On the conduct of police officials, against whom the Commission had made adverse comments, he said "we will see what can be done within the ambit of law."

The government would provide assistance to all Sikh families affected by the riots to enable them to lead a life of "dignity and self-respect", Singh said.

Asserting that Nanavati Commission had nailed the lie that top Congress leaders were involved in the 1984 anti-Sikh riots, he said the government stood committed to further investigate cases against all those named by the one-man panel.

"This lie has been used for the past 21 years to poison the minds of Sikh youths. This lie stands nailed conclusively," he said.

"You have my assurance that our government stands committed to doing all that law humanly permits to get to the root of the problem. All those against whom the Commission drew adverse inference, we will have a re-look at them," the prime minister added.

Recalling that it was the late Rajiv Gandhi who had brought peace to the militancy-hit Punjab by signing an accord with Longowal, Singh said that after the 1984 tragedy, the topmost thing Gandhi had in his mind was how to bring Punjab to the national mainstream.

He appealed to all to work steadfastly for mutual reconciliation and quoted Father of the Nation Mahatma Gandhi, "the endeavour should be to wipe out every tear from every eye in the country".

Stressing that nothing should be done to weaken the self-confidence of the Sikh community, Singh said the 1984 anti-Sikh riots should be viewed from "wider perspective" that the past cannot be brought back or undone.

He said people should desist from doing anything that leads to a kind of trauma witnessed in "Delhi or in Gujarat or in any other part of the country". He urged members not to create a situation which will give a boost to forces inimical to the country's unity and integrity.

1984 riots, a national shame: PM