The government is set to appeal a ruling that could see Apple forced to pay billions of euro in back taxes.

The European Commission is set to rule this week on whether the tech giant was given unfair state aid by being allowed to negotiate its tax rate.

The ruling could see Apple paying taxes for the last ten years - with one estimate from JP Morgan putting the sum at €19 billion euro.

Authorities in Brussels have been investigating an alleged 'sweetheart' deal between Ireland and Apple since 2013.

Ireland has always insisted its tax rate is based on law, which makes it highly transparent - but the Commission says it has evidence that in 1991 and 2007, Ireland reached a private agreement with Apple, effectively to agree how much tax Apple should pay.

The complex loophole used by Apple - and many other firms - was shut under Budget 2015, which included a clampdown on so-called 'stateless corporations'.

Before then, under Irish law, a firm was only liable for tax wherever its main centre of business is - but under American law, a firm is only liable for tax in whatever country it is registered.

This situation meant that Apple's global operations firm - with its main business operations in the USA, filtering worldwide revenue through a firm registered in Ireland - didn't have to pay tax in either.

And with other internal trading between Apple firms rolled in, its effective corporate tax rate in Ireland has often been less than 1%.

Sinn Féin says the decision should not be appealed - but that before any decision is taken, the Dáil's finance committee should be recalled to discuss the outcome.

SF's Pearse Doherty sits on that committee:

Earlier, our political correspondent Gavan Reilly filed this report for Today FM's National Lunchtime News: