"Twenty-one crew members moved to life rafts and from them to [South] Korean rescue vessels," the spokesperson said.
"Four people — the chief mate [captain] and three others — remained on board; the search for them is underway; there are complications due to the fire."
Citing South Korea's Coast Guard, local media reported earlier Friday that a Russian fishing boat with 25 crew members aboard, all Russians, and carrying some 100 tonnes of seafood in waters off Ulsan, about 300 kilometers (186 miles) southeast of Seoul, caught fire while sailing back to Russia.
The Coast Guard sent rescue ships after receiving a distress call and saved 21 crew members, 19 of them were unharmed, and 2 sustained minor injuries. Another four crew members went missing.
A spokesperson for the Far Eastern Transport Prosecutor's Office told Sputnik that the fishing boat's name was Kaltan, and it was from the city of Vladivostok.