An explosion at a Ukrainian coal mine killed at least 16 miners on Friday and nine were missing, the Emergencies Ministry said.
Three miners were also hurt in the explosion at the Sukhodilska-Eastern mine in the Luhansk region, the former Soviet republic's coal mining heartland, it said in a statement.
"The cause of the blast is being determined," the ministry said. Interfax news agency quoted a regional mining official as saying the explosion was caused by a concentration of methane gas inside the mine, where 252 people were working at the time.
The explosion in the early hours of Friday morning was the deadliest since 2007, when a methane blast at a nearby mine killed more than 100 people.
Ukraine produced more than 75 million tonnes of energy and coking coal last year, but has been plagued by accidents caused by poor infrastructure and lax safety regulations.
The mine is owned by Krasnodon Coal, Ukraine's second largest mining company which is part of Metinvest, a firm run by Ukraine's richest man, Rinat Akhmetov. Akhmetov's SCM owns 71.25 percent of Metinvest.
The mine, which has been in operation since 1980, accounts for a quarter of Krasnodon Coal's output. In 2009, Krasnodon Coal's total coking coal output was 5.4 million tonnes.
In 1992, 58 people were killed in a methane explosion at the same mine. A fire broke out at the mine last month but no one was hurt.