The US government is looking to intervene in Apple’s appeal against a $13 billion European tax bill, imposed after the iPhone maker received what were described as “illegal subsidies”, Bloomberg reported.

An unnamed source apparently said: “I can confirm the United States filed an application with the European Union General Court to intervene in the case involving the retroactive application of state aid rules to Apple.”

The issue stems from what has been tagged “sweetheart” tax deals Apple agreed with the authorities in Ireland, which were subsequently tagged as illegal subsidies following a probe by the European Commission (EC).

It said the deals enabled Apple to pay a tax rate of 1 per cent or less for a number of years.

Unsurprisingly, the US action is driven by a desire to keep the cash within a US company, in the hope it will be able to get a chunk of tax itself. Bloomberg reports the Trump administration has proposed tax breaks for US companies bringing home cash held overseas, in a move which would nevertheless provide a good source of income for the government.

Apple is well-known for having large cash reserves overseas, as are tech peers such as Alphabet and Cisco which also have significant international operations.

The US tech giant and the Irish authorities have already appealed the judgement, with the latter arguing the EC had exceeded its powers, and misunderstood the relevant facts of Irish law.