New Delhi, June 16 (IANS) The Bharatiya Janata Party (BJP) Wednesday alleged there was "high level government involvement" in helping then Union Carbide chief Warren Anderson leave the country after the 1984 Bhopal gas tragedy.

"It is too well known from the beginning, there has been foul play. It (Bhopal gas tragedy) is a non-bailable offence, yet not treated that way. The then chief minister, prime minister are all accountable. There was high level government involvement to let him out of the country," BJP spokesperson Ravi Shankar Prasad told IANS.

Congress leader Arjun Singh was chief minister of Madhya Pradesh and Rajiv Gandhi the prime minister in 1984.

Prasad's comments came a day after IANS reported that Anderson was promised safe passage by the Indian government even before visiting India following the Bhopal gas tragedy.

A former US diplomat, who was the deputy chief of mission at the American embassy in New Delhi, told IANS that Anderson came to India only after getting an assurance of "safe passage" from the Indian government.

Anderson, 89, is now retired and lives in the US.

On the night of Dec 2-3, 1984, lethal gas leaked from Union Carbide's pesticide plant, killing over 3,000 people instantly and many more over the years. There has been outrage in India over a court handing out a prison sentence of two years to seven accused after all these years.