More than 30 people have been killed in a coal mine in a separatist stronghold of eastern Ukraine after an explosion at the facility, Ukraine’s parliamentary speaker has said.

Volodymyr Groysman’s announcement came after local officials and media reported earlier on Wednesday that dozens of miners were trapped in the Zasyadko mine of Donetsk city.

“Rescue workers have not yet come to the place of the explosion, they are removing the poisonous gas and then will go down,” said Vladimir Tsymbalenko, head of the local mining safety service on Wednesday.

Separatist authorities in Donetsk said in a statement that the blast occurred at a depth of more than 1,000 metres and that 230 workers were in the mine at the time.

The statement said the explosion was caused by a mixture of gas and air – a common cause of industrial mining accidents.

According to the rebel officials, at least 157 miners have been evacuated from the mine.

The Zasyadko mine was the site of another accident in 2007 when more than 100 miners were killed in a methane explosion. Al Jazeera