US Treasury Secretary Jacob Lew has criticised the European Commission's investigations into tax arrangements in EU member states during a meeting with Minister for Finance Michael Noonan.
The two met at the US Department of the Treasury in Washington DC yesterday.
A statement from the Treasury Department said that they had discussed "recent economic developments in Ireland, the euro area and the global economy".
They also spoke about the ongoing EU state aid investigations being carried out by the European Commission involving US companies.
The statement said that Mr Lew had "reiterated his concerns" that the commission was retroactively applying "a sweeping new state aid theory" that was "contrary to well established legal principles".
He said it called into question the tax rules of individual member states and threatened to "undermine the overall business climate in Europe".
Mr Lew told Mr Noonan that they shared "the goal of addressing corporate tax avoidance", and highlighted the "meaningful progress" already made between the US and the EU.
They also discussed Brexit and the economic fallout from that, with Mr Lew pledging that the US was "committed" to working with the EU and the UK to "ensure sustained economic stability and shared, global prosperity".
Mr Lew said that a "transparent, smooth and cooperative process" was in the best interests of Europe, the US and the global economy.
He also said that the Treasury Department was "committed to a smooth transition" to the Donald Trump administration.
Mr Noonan also yesterday met officials from the International Monetary Fund and the World Bank.
He will travel to the west coast later today for some more meetings with individuals described as key business interests.
It is understood he will visit several companies in the Silicon Valley area that have operations in Ireland.