Supermarkets have come under fire for running wide-ranging deep-discount toy promotions in the run-up to Christmas.

Sainsbury’s - which has previously offered all toy lines at half-price in the run-up to Christmas- is currently selling many big brands at a half or third off, including the Nerf Elite blasters launched two months ago, which are on sale for 50% off. Asda and Tesco have also been promoting, with Tesco describing its latest push, which ended this week, as ‘Our Biggest Ever Toy Sale’.

Suppliers and specialist toy retailers warned that many shoppers now only bought goods on promotion and that supermarkets were devaluing the market.

“As soon as price is eroded, the customer assumes the quality of the product is devalued,” said one supplier.

He also suggested the intense promotional activity stifled NPD. “Buyers cry out for innovation year-in, year-out, but it is no wonder the level of innovation has slowed when, in the first year of release, that investment is being heavily devalued at retail.”

While driving footfall was a key reason for the promotions, supermarkets were also keen to encourage shoppers to start their Christmas spending earlier, said Jez Fraser-Hook, UK toy director at analysts NPD Group. In 2011, 40% of the UK spend on toys came in the last two months of the year, with 23% in December alone.

Supermarkets were running toy promotions earlier every year, said one specialist retailer. “Get closer to Christmas and the supermarkets won’t be promoting toys, it will all be food and booze,” he said.

Sainsbury’s claimed it was only trying to meet consumer needs. “Christmas is an expensive time of year and every penny counts,” said buyer Tom Folliot. “By discounting toys by up to half price we can help lighten the load.”