Margaret Thatcher pleaded with Charles Haughey to help her crush the Argentinians at the outbreak of the Falklands War, it has been revealed.
Confidential files show the then British prime minister personally urged the Taoiseach to "hit them hard" by halting overseas trading with the South Americans.
Mrs Thatcher admitted she had been forced to turn to "close friends" for support because she suspected the Soviet Union would block any United Nations (UN) proposed sanctions.
"I now seek your personal help to bring about the urgent introduction of economic and financial measures against Argentina, by national action co-ordinated among us," she wrote to Mr Haughey.
In the message, marked "personal and confidential", the Tory leader said Argentina had made clear it would defy a UN Security Council resolution issued on April 3, 1982 to withdraw its forces from the Falkland Islands.
Calling for all available means to be brought to bear on the invading troops, Mrs Thatcher said economic and financial measures would have a particularly powerful impact. The British premier openly accepted that sanctions would hit the Irish economy as much as Argentina's.
"I know that these measures will affect your own economic interests," she said in the message, released into the National Archives in Dublin from the Taoiseach's department.
But she insisted they would bring the Argentine government "to their senses" and quickly lead to a peaceful withdrawal of troops from the disputed territory off Argentina in the south Atlantic.
As well as a complete ban on the supply of arms, an embargo on all or some imports from Argentina, Mrs Thatcher sought an Irish ban on export credit guarantees and international lending to the south American country. Predicting that international money markets would cease loans to Argentina because of the economic upset, she appealed to Mr Haughey: "I ask you to provide no incentive and no encouragement."
The State papers show Mrs Thatcher made similar pleas to the United States, Japan, Canada, Australia and New Zealand.