Universal's attempt to put together an online music service to rival iTunes has fallen foul of US regulators.

Universal and Sony-BMG have been touting plans for an online music retail service called Total Music. A service the two major labels hope will reduce Apple's dominance of digital music retail sales.

However with Universal and Sony-BMG between them accounting for around 50 per cent of the world's total sales of music, officials from the US Department of Justice (DoJ) have called the labels in to ensure no anti-competitive anti-trust market shenanigans.

Both labels have received letters from the DoJ asking them about their plans as regulators begin an enquiry into the consequences of the plan.