Union Carbide Corp. said yesterday that it suffered an "extraordinary" $17.8 million loss in the last three months of 1984 as a result of the disaster in Bhopal, India, that killed more than 2,500 people in early December.

But financial analysts said the loss -- which reduced company profits for the year from $341 million to $323 million -- was only a small fraction of the potential costs to Union Carbide arising from the worst industrial accident in history.

The $17.8 million loss, which amounted to 25 cents per share, covered only such items as the company's contribution to emergency relief funds for victims of Bhopal, shutdown of the five plants that manufacture or use the toxic chemical methyl isocyanate that caused the accident, and refusal of officials in Brazil and France to accept company shipments of the chemical, a spokesman at the company's Danbury, Conn., headquarters said yesterday.

The loss does not include any potential liabilities arising from the numerous lawsuits that have been filed against the company as a result of the disaster, said company spokesman Stephen Galpin.

"If this was the only loss Carbide was facing, they would be turning cartwheels in Danbury, Conn., right now," said Paul T. Leming, an analyst with Kidder, Peabody & Co. in New York. "This has absolutely no bearing on what happens to the company over the next six months to 10 years."

If anything, another analyst said, the company's reported profit of $341 million (excluding the $17.8 million loss) on revenue of $9.5 billion was somewhat disappointing.

The company acknowledged in a statement that its earnings reflected "weak results" in its petrochemical and metals and carbon products. Anthony Pearce-Batten, who follows the company for the Baltimore firm of Legg Mason, said the results showed Carbide's "overdependence on declining industries," such as steel.

According to Carbide's release, the company's pre-Bhopal preliminary net income for the year came to $4.84 per share, compared with profits of $218 million ($3.11) for 1983.