The two Chinese seafarers said the vessel, called the Ocean Winner, had begun to tilt on Friday and sank within eight minutes, forcing the crew to abandon ship, India's Maritime Administration director general Shyam Jagannathan told Reuters.
Jagannathan said the chances of finding survivors generally fall sharply after the first 12 hours but rescuers were continuing their search.
"All agencies are co-ordinating closely and actively doing search and rescue efforts," ports minister Sarbananda Sonowal said in a social media post.
The missing crew members include 18 more Chinese citizens, three from Myanmar and one Bangladeshi, according to India's coastguard.
The Indian navy is closely co-ordinating with the coastguard to locate the missing seafarers, the navy said in a social media post.
Two coastguard vessels from Sri Vijaya Puram, formerly known as Port Blair, the capital of India's Andaman and Nicobar archipelago, were dispatched for the search-and-rescue operation, a coastguard spokesperson said.
The Ocean Winner was carrying iron ore bound for China after departing from India's eastern Paradip port on Friday, according to an initial report prepared by India's Maritime Administration.
It sank about 240 nautical miles from the port, according to government sources.
The cause of the sinking was not immediately known.
