The Ukrainian emergency ministry raised the toll from 16 to 18 from an explosion early July 29 at the Sukhodolskaya-Vostochnaya coal mine in the eastern Lugansk region.

Eight miners were still missing on July 30 after that blast deep in the mine, likely caused by a buildup of deadly methane gas, while two remained hospitalised with serious burns.

The death toll from a separate accident hours later also rose to seven, and four miners remained missing on July 30 after a mine headframe collapsed at the Bazhanova pit in the town of Makiyivka in the neighbouring Donetsk region.

The twin disasters were the country's worst mining accidents since more than 100 miners died in a mine explosion in 2007.

The blast at the Sukhodolskaya-Vostochnaya mine rang out at around 2 am on July 29, in an air passage more than 900 metres (2,953 feet) deep in the mine, where 28 miners were working at the time, the local emergency ministry said.

On July 30, "eight miners remained trapped in the disaster zone," the ministry said, without indicating whether they were likely to be alive.

Rescuers were removing gas from an emergency access tunnel into the mine, in order to go down in search of the missing miners, a spokeswoman for the Lugansk regional administration said.

But she said there was little hope of finding more miners alive.