Royal Mail has blamed strike action for helping send it slumping to a full-year loss of more than £1 billion.The group's owner, International Distributions Services, revealed Royal Mail swung to an operating loss of £1.04 billion for the year to March 26, against earnings of £250 million the previous year.On an underlying basis, Royal Mail saw operating losses of £419 million, against profits of £416 million the previous year.

Royal Mail has blamed strike action for helping send it slumping to a full-year loss of more than £1 billion.The group's owner, International Distributions Services, revealed Royal Mail swung to an operating loss of £1.04 billion for the year to March 26, against earnings of £250 million the previous year.On an underlying basis, Royal Mail saw operating losses of £419 million, against profits of £416 million the previous year.