Taoiseach Enda Kenny has condemned as "mischievous, misleading and wrong" any suggestion that the European Commission had opened any other state aid investigations into Ireland.
He described the suggestion as "very damaging" to Ireland and said that he took the matter "very seriously".
Mr Kenny was responding to a report in The Irish Times that the European Commission had not ruled out further investigations into Ireland's tax arrangements with multinationals, and that the commission was assessing up to 300 cases relating to Ireland.
The Taoiseach told reporters at the end of the EU summit in Brussels that the commission's directorate-general for competition had asked the Irish authorities in 2013 for information on all tax rulings - arrangements between multinationals and the Irish tax authorities - between 2010-2012.
He said that as a result of the request, only one investigation had followed, which was the Apple probe.
"The commission attended with the Revenue Commissioners in reviewing these [rulings] and the commission subsequently launched a state aid investigation in 2014 in respect of one case only," said the Taoiseach.
"No other state aid cases have been opened against Ireland arising from the information submitted to the commission, nor have we any indication that there are any other cases under consideration.
"That is not to say that at some future point the commission might not want to reverse that."
Mr Kenny added: "In the interests of the international focus on Ireland as an investment-attractive country, the commission have never stated that there are other impending state-aid cases against Ireland.
"To suggest otherwise is mischievous, is misleading and is wrong.
"That type of loose talk is potentially very damaging to our country and I take the matter very seriously indeed."
Mr Kenny said he had already received "a number of queries" about the issue.
In August, EU Competition Commissioner Margrethe Vestager announced that Apple had benefited from a preferential tax deal with the Irish Government to a total of €13 billion.
The Revenue Commissioners have until later this month to work out exactly how much Apple owes in unpaid taxes, based on the commission's methodology.
The company has until 31 December to place the amount into an escrow account.
The Government strongly condemned the decision and has said it will appeal it to the General Court of the European Court of Justice.