Margaret Thatcher's government was desperate to stop cash from the Soviet Union reaching the striking coal miners, according to newly-released Government papers.
Official files from 1984 released by the National Archives show ministers believed hundreds of thousands of pounds were being channelled to the National Union of Mineworkers (NUM) from Moscow.
But even though the union's assets had been sequestered by the courts after its president, Arthur Scargill, refused to allow it to pay a £200,000 fine for contempt, officials admitted there was little they could do to stop the flow of roubles.
Mrs Thatcher was told the best they could hope for was that a NUM courier might be picked up by Customs trying to enter the country with "a suitcase full of bank notes".
Minsters were alerted by MI5 to the Soviet financial lifeline for the miners in early November 1984. A few days later the Soviet news agency TASS reported publicly that £500,000 had been raised to support the strike.
Although the money was supposed to have been donated by Russian miners, the Government had little doubt that the funds could only have been transferred abroad with the approval of the Soviet authorities.
Margaret Thatcher secretly considered calling out the troops at the height of the miners' strike amid fears union action could destroy her Conservative government, according to newly released files.
Government papers from 1984, released by the National Archives, show ministers were so concerned at the outbreak of a national docks strike while the miners were still out, they considered declaring a state of emergency.
Plans were drawn up for thousands of service personnel to commandeer trucks to move vital supplies of food and coal around the country.
It was probably the closest Mrs Thatcher came to defeat in her battle with the miners but the scheme was never implemented after the dockers' action petered out after less than two weeks.
The epic, 12-month confrontation between the Conservative government and the National Union of Mineworkers (NUM) and its left-wing president Arthur Scargill was one of the defining episodes of the Thatcher era.
It saw some of the worst industrial violence the country had witnessed, with hundreds injured in brutal picket line clashes between police and miners, and ended in crushing defeat for the NUM.
As Prime Minister, Margaret Thatcher's immaculately coiffed blonde locks were as much a part of her image as her famous handbag - and newly-released government files show just how much time she spent keeping up appearances.
Her appointments diary for 1984, released by the National Archives, show that she had 118 hair appointments in the space of 12 months.
In June, when she was hosting world leaders at an economic summit in London she had hair appointments on five consecutive days.
The diary also confirms her reputation as a workaholic who found it difficult to relax.