NATIONAL strikes by postal workers will go ahead tomorrow and Friday after hopes of reaching a last minute deal collapsed.

Up to 120,000 members of the Communication Workers Union (CWU) will stage two 24-hour walk-outs, crippling mail deliveries across the country.

The union warned of further strikes in the coming weeks and launched an extraordinary attack on Business Secretary Lord Mandelson, saying he was working hand in hand with the Royal Mail to undermine the dispute.

General secretary Billy Hayes accused him of being the minister without responsibility.

Dave Ward, the union's deputy general secretary, said the Royal Mail had no intention of resolving the dispute and seemed intent on "sidelining" the concerns of postal workers.

Mr Ward, who led the union's negotiators during marathon peace talks, said he believed progress had been made and that a deal could have been agreed which would have averted the strikes.

But he said a letter sent today to the union by Royal Mail managing director Mark Higson had "wiped out" progress which had been made during the talks and scuppered the chances of a deal.