Six children were among the dead, the emergency situations ministry said in a statement, while six people had been rescued from the rubble of the building in the Ural mountains city of Magnitogorsk.

The explosion tore through the 10-storey building in the industrial city nearly 1,700 kilometres (1,050 miles) east of Moscow in the early hours of Monday.

Officials had given a toll of 28 dead as of late Wednesday.

Rescuers have been braving freezing temperatures to search through mangled concrete and metal but no survivors have been found since Tuesday, when a baby boy was pulled from the rubble.

The Soviet-era apartment block was home to about 1,100 people and the explosion left dozens homeless over the New Year — the biggest holiday of the year in Russia.