The Irish Government queried Sinn Fein receiving a postal discount for sending bulk mail to the US over concerns it was helping to fund the IRA.
Sinn Fein wrote to various companies and people appealing for donations to the party, and has received millions in funding over the last three decades.
Declassified documents released in Dublin show that an Irish Government minister queried whether he could prevent a discount deal between Sinn Fein and An Post for sending bulk mail to the United States.
There were concerns that some of the funds raised in the US would be used to support the IRA rather than to "fill the election coffers of Sinn Fein".
A confidential letter sent in November 1988 shows that the then Communications Minister Ray Burke sought to use his powers under the Postal and Telecommunications Services Act 1983 to order An Post not to make an arrangement with the party.
The letter from assistant secretary Dermot Gallagher also noted that a direction by the minister "may create trouble in terms of Sinn Fein propaganda or even court actions".