Moscow ? A methane gas explosion deep in a Siberian coal mine killed at least 78 people and left another 50 trapped Monday in Russia’s worst mining disaster in a decade.

Among the missing were company officials and safety experts who had been inspecting a British-made hazard-monitoring system, said Sergei Cheremnov, a spokesman for the regional government in Kemerovo, where the mine is located, about 1,850 miles east of Moscow.

A British man and his interpreter were among those killed, he said. It was unclear what the two were doing in the mine.

Up to 200 workers were in the Ulyanovskaya mine when the explosion occurred about 885 feet underground in the coal-rich southern region known as the Kuzbass, emergency and regional officials said. At least 75 people were rescued.

Rescuers were checking a large section of the mine for the missing people and were in contact with some of the surviving miners, officials said. It was unclear if the survivors were in immediate danger. At least five miners were injured.

The mine is in the city Novokuznetsk, the site of two of the deadliest mine disasters in the past decade. In 2004, a blast at a mine on the outskirts of the city killed 47 workers, and in 1997, a methane explosion killed 67.