Weeping relatives gathered in cemeteries around Donetsk, heart of the Donbass coalfield, on Tuesday to bury the dead from Ukraine's worst mining accident.

Flags in the ex-Soviet state were adorned with black ribbons and flew at half mast on a national day of mourning for at least 89 people killed in Sunday's methane blast.

Coffins draped in maroon cloth were lowered into four graves at the vast, dusty Shcheglovskoye cemetery, a resting place for victims of previous disasters and lying within sight of the Zasyadko mine.

At least 10 Zasyadko miners are still missing after fires roared through shafts more than 1 km underground.

Trade union officials say there is little chance they are alive. Thirty remain in hospital.

An orchestra played as families were joined by veteran miners and industry officials. Other miners stood at a respectful distance behind a fence.

It is a terrible sight when they bring the bodies to the surface, said ex-miner Anatoly. They are incinerated. All but impossible to identify after death in such conditions.

All but one of the coffin lids was kept shut.

The mine's general director, Yefim Zvyagilsky, burst into tears as he addressed families: Parents, wives, children. I share in your indescribable suffering. Our mine will help you. No request for help will go unanswered.

Three busloads of miners passed on their way to start the next shift. Altogether 28 miners were buried throughout the region.

Until Sunday, post-Soviet Ukraine's worst mining accident had been in March 2000, when an explosion killed 80 miners at a pit near the eastern town of Luhansk.

Zasyadko is viewed as one of Ukraine's most technologically advanced and profitable pits. Miners earn on average each month the equivalent of $1,000 -- more than three times the average national wage -- with those at the coalface getting still more.

But Sunday's blast was the fourth major accident there in six years. At least 225 miners have died since 1999.

Vitaly, a middle-aged miner, is wondering whether it is worth carrying on. I know three colleagues who want to quit, he said. But I have three children, so what am I to do?

My small daughter never leaves my side now. She is afraid that she could lose her dad.