Parents can buy a complete clothing set of a round neck sweater, two polo shirts and a skirt or pair of trousers for £4.
By contrast, similar items at mainstream supermarkets Tesco, Asda and Sainsbury’s are around 46 per cent higher, ranging from £6.75 to £7.50.
Aldi is charging £1.25 for a child’s round neck sweater, while Sainsbury’s and Asda charge £2 and Tesco £3 for such an item. Likewise, trousers or skirts cost from £3 at Sainsbury’s and Asda and from £1.75 at Tesco, while Aldi has the products from £1.50.
The price war follows reports that the German discounter plans to double its UK stores to 1,000.
Meanwhile, mainstream supermarkets such as Tesco – Britain’s biggest retailer – are seeing growth slow as shoppers hit by the economic downturn seek out cheaper options.
In recent years, many schools have loosened uniform policies, giving parents more flexibility on where school clothes can be purchased – such as offering children the option of wearing a plain sweatshirt or jumper rather than a more expensive one emblazoned with the school’s logo.
Anti-poverty campaigners warned of a “direct correlation” between low prices and poor working conditions for manufacturers overseas – although Aldi insists its products are all manufactured in line with its ethical standards policies.
Tina Woolnough, spokeswoman for the National Parent Forum of Scotland, said: “Parents welcome good quality, hard-wearing school uniforms at affordable prices.
“Most schools do have fairly standard uniforms now, which offer flexibility in terms of where they can be purchased. That has changed quite a lot over the last few years and school do recognise that families are stretched financially and every penny helps.”
.John Hilary, executive director of anti-poverty charity War on Want, said: “We are not naive and we know that even the high-end producers don’t have to pay good wages.
“However, when you demand such low prices, that forces costs down all the way along the supply chain. There is a necessary correlation between very low prices for consumers and worse conditions for workers.”
Aldi was recently named Britain’s top brand for this year in YouGov’s brand index poll.
A spokeswoman for Aldi said its school uniform range complies with its “social monitoring programme” which, it says, requires audit reports from final production sites to ensure they meet its standards.
Aldi was one of 200 retailers to sign the Accord on Fire and Building Safety for factories in Bangladesh, following the Tazreen Fashions fire in 2012 and the collapse of the Rana Plaza factory in April last year, which together resulted in 1,200 deaths.