(Adds details on Chinese killed, editorial)

SEOUL, Jan 8 (Reuters) - The death toll from a fire that ripped through a warehouse under construction outside of Seoul has risen to 40, officials said on Tuesday, with most of the victims overcome by toxic fumes.

The fire in Icheon, about 60 km (40 miles) southeast of the South Korean capital, started on Monday and triggered several explosions.

Fire officials said most of the victims were construction workers trapped inside the basement of the refrigerated goods facility who could not escape a toxic cloud of gas that came from burning insulation material.

The fire is the deadliest in South Korea since a blaze in the subway system of Daegu, 250 km southeast of Seoul, killed nearly 200 people in 2003.

The victims included 12 ethnic Koreans who are Chinese citizens, the Chinese embassy in Seoul said. South Korean Foreign Minister Song Min-soon plans to send a condolence letter to China's foreign minister, Song's ministry said.

Ethnic Koreans living in China often come to richer South Korea looking for work.

The exact cause is not yet known but local media said authorities were investigating whether gas caught fire in a basement engine room at the warehouse, starting the blaze.

Ten workers, including one ethnic Korean from China, were taken to hospital and another seven escaped without major injuries, fire officials said. More than 600 fire fighters and police were dispatched to the scene.

The country's biggest newspaper, the Chosun Ilbo, said in an editorial on Tuesday it appeared as if little concern was paid to the safety of the construction workers.

"No matter how much our economy grows, a country where people's lives are wasted this way cannot be called an advanced nation," it said. (Reporting by Jon Herskovitz and Mee Hyoe Koo; Editing by Sanjeev Miglani)

AlertNet news is provided by