The stand-off between the European Union and United States big tech companies looks set to continue after the US ambassador to the bloc warned it was up to the EU to prove that new rules on digital practices did not discriminate against US companies, if it wanted to ensure "a good relationship going forward".

In an interview with the Financial Times newspaper, Andrew Puzder backed up US President Donald Trump's support for US tech firms in the light of European legislation covering the digital sector, which aims to discourage the market dominance of a small number of big tech companies, many of which hail from the US, in the name of consumer protection and freedom.

No US president, Puzder said, "can sit back and allow these kinds of infringements on Americans' fundamental rights or, in fact, on American companies… so we're going to have to either determine that that's not what's happening, or we'll have to make some changes so that it isn't what's happening".

The EU's executive arm, the European Commission, is currently holding a consultation about legislation including the Digital Markets Act, or DMA, and Puzder, who only took up his post this month, insisted he would make sure "to have some discussions about where the real points of disagreement are and how they can be addressed".

"The Europeans believe that (the rules) are less restrictive and less targeted than the US believes, and I think we're going to need to sit down and go through these acts with some care."

The policy of global tariffs introduced by Trump in the spring has resulted in many EU exports to the US being subject to 15 percent taxes, and in early September he said "substantial additional tariffs" and export restrictions could be imposed on countries whose digital policies were felt to target US companies.

Commission Executive Vice-President Henna Virkkunen replied by saying that the DMA and the Digital Services Act, or DSA, were "sovereign legislations" applying equally to all online operators in the bloc, and did not discriminate against any entity.

Apple recently called for the legislation to be scrapped altogether, Google has been heavily critical, and Mark Zuckerberg, chief executive of Facebook's parent company Meta, personally lobbied Trump over the issue, but the Commission shows no sign of bending.

"It seems from my meetings here in the EU, there is a very distinct disagreement as to what the (DMA and DSA) do, what their effect is", Puzder said, adding "Europe has every right to legislate as it chooses. But I think it would be good if we could have an understanding of each side's points on this before we get too far along".

The consultation ends on Oct 14, and Puzder added "If the intent is to inflict economic pain on competitors outside of Europe to help European companies, that's something that the US would object to vehemently".

"Obviously, if we're going to have a good relationship going forward, you can't have legislation that punishes companies from . . . your ally."