Toy retailers selling Bigjigs stock on third-party websites like Amazon, eBay and Play.com have two weeks to pull the product listings - or be cut off by the supplier.
Earlier this year, manufacturer, distributor and wholesaler Bigjigs Toys made the announcement that is no longer supporting retailers who trade on such sites.
The changes come into effect on Saturday, June 1st.
A Bigjigs statement read: "Bigjigs Toys have reiterated that they are no longer willing to allow their brand to be devalued by the price wars on these third-party websites and will continue to champion and support their High Street retailers.
"The company will monitor all such sites after the June 1st deadline and any customer accounts found to be listing will no longer be supplied by the UK's leading wooden toy manufacturer."
When I Was A Kid owner Paul Warner said: "If I had a cap, I would be doffing it. I think this is an awesome stance to take and has really underlined Bigjigs' credibility and reputation as not only a true supporter of independent toy shops, but also a company with a sense of right and wrong that is far greater than the narrow minded 'profit at any cost' stance taken by so many toy suppliers in this fickle world we trade."
Retailer Down To The Wood added on Twitter: "Well done @bigjigstoys we will up our orders now you’ve made a stand against third party online sales. No more #showrooming."
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