American former CEO Warren Anderson was arrested in India after the accident, which killed tens of thousands of people, but he then fled the country.
Requests for his extradition were turned down by US authorities.
He -- like the local managers of Union Carbide's subsidiary in India -- faced charges of criminal negligence. Seven of the local managers were finally convicted on Monday, while Anderson was named as an absconder.
Amid anger in India about the perceived leniency of the sentences given to the Indian managers -- two years in prison pending appeal -- Anderson has again become a target and a lightning rod for a general feeling of injustice.
"As far as Anderson is concerned, the case is not closed," Indian Law Minister Veerappa Moily said.
"There is one person here who has not responded to the summons or replied to the charges. He has absconded and was declared a proclaimed offender," he told the Press Trust of India.
Indian politicians, campaigners and newspapers vented outrage at the prison terms handed to those found guilty for the accident, which saw a cloud of toxic gas poison the slums surrounding the factory in the central Indian city.
Scorn was heaped on the 25-year delay in the convictions and fingers were pointed at Anderson in a slew of news reports and during chat shows on cable television.
The prosecution argued in the Bhopal court that there were design defects in the factory as well as other criminally negligent operational practices that were known to management but ignored for commercial reasons.
Anderson lives in suburban New York, and the Hindustan Times blamed the Indian government for allowing him "to live a life of ease far away in the US while the victims struggle from day to day".
The ageing former executive is unlikely to ever return to India and no one in New Delhi expects an extradition to be approved, so there appears little chance of him answering the charges in an Indian court.
The investigator who handled the Bhopal case from 1984 to 1995, B.R Lall, said he was instructed not to press for the extradition of Anderson by the ministry of external affairs, The Express newspaper reported.
"Monday's convictions do not matter because these were foot-soldiers," he was quoted as saying.
In a statement on Monday, the company said the appropriate people had faced trial, arguing that US executives were not involved in the day-to-day running of their majority-owned subsidiary, Union Carbide India Ltd.
The two-year sentences were the maximum that could be imposed after the Supreme Court in 1996 reduced the charges from culpable homicide to negligence. Many survivors said the guilty should be hanged. One survivor, Champa Devi Shukla, said she "felt like an idiot holding a placard outside the court while the accused left in big cars".
"Shame On India" headlined the Mail Today, while the front page of The Times of India read: "Justice Delayed, Denied."
Dow Chemical bought Union Carbide in 1999 and says all liabilities related to the accident were cleared in a 470-million-dollar settlement reached out of court with India's government in 1989.
Government figures put the death toll from the accident at 3,500 within three days of the leak, but the state-run Indian Council of Medical Research puts the figure at between 8,000 and 10,000 in the same period.
The ICMR has said that up to 1994, 25,000 people also died from the consequences of gas exposure, and victims groups say many are still suffering the effects today.
After the verdicts, other commentators saw repercussions for controversial legislation that the ruling Congress-led government is trying to pass to cap the legal liabilities of US nuclear firms operating in India.
The measure is key to putting into operation a 2008 civilian nuclear agreement with the United States that will give India access to US nuclear technology.
Source: AFP Asian Edition