We are determined to win this battle, however long it may take South Wales miner

NCB Chairman, Derek Ezra, said: "If we had granted the �120m they had asked for and thus presumably satisfied the mineworkers, we would have landed ourselves in a very serious financial situation.

"The only way of recouping that money would then have been to put prices up and we would have had to put the price of coal up by at least another 15%."

Mr Ezra said the strike would mean up to �12m a week in lost revenue - and therefore calculations on which previous pay offers had been made were invalid.

The Trades Union Congress (TUC) is holding meetings at the weekend to discuss support for the strike among transport unions.

The General Secretary of the National Union of Mineworkers, Lawrence Daly, has predicted coal stocks will quickly run down.

"Industrialists in this country will be pressing the Government to get the door open for serious talks," he added.

Three-quarters of the electricity used in the United Kingdom comes from coal-burning power stations.

The strike comes at a time when the stations are facing long periods of peak demand during the cold weather.

All 289 pits across the country have been closed by the strike. Miners say they are prepared for a long fight.

A south Wales miner said: "We are going into this now, not thinking it's going to be over in a week or a fortnight. We are determined to win this battle however long it may take."

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