Seven dead in Kazakh mine blast

At least seven people have died and more than 20 are missing after an explosion at a coal mine in the central Karaganda region of Kazakhstan.

The explosion occurred in a mine owned by the world's largest steel-producing firm, Arcelor Mittal.

Rescue attempts were hampered by a fire raging underground and an official said there was "no guarantee" the missing men would be found alive.

In 2006, another explosion in a mine in the Karaganda region killed 41 miners.

Kazakh Deputy Prime Minister Umirzak Shukeyev, who visited the scene, said the rescue effort would continue through the night.

Some 190 miners were working underground at the time of the blast.

Nurlan Nigmatulin, governor of Karaganda region, told reporters: "Seven people have been killed, 23 are missing. We don't know what happened to them."

Reports say at least 12 miners were treated for burns and other injuries.

'Deep regret'

In a statement, the billionaire founder and chief executive of Arcelor Mittal, Lakshmi Mittal, said he "deeply regretted" the accident and that the safety of workers was the company's "number one priority".

He said there had been significant efforts to improve the health and safety of miners and an investigation would now take place into the cause of the blast.

"We are doing everything we can to locate those still missing and to assist the bereaved," he said.

Officials have not confirmed the cause of the blast but previous mine explosions have been the result of a build up of methane gas underground.

Vyacheslav Sidorov, head of the local Korgau miners union, told AFP news agency that the condition of the mines was "frightening".

"The mines are old, they need to be completely modernised, the equipment needs to be upgraded and the pay scale needs to be revised," he said.