Irish retailer Penneys says some of its products are being re-sold by third parties, at higher prices, through Amazon.
It says it does not have a commercial partnership with the online shopping website.
It comes after some newspaper reports that it had set up an online shopping service.
The retailer - which trades as Primark outside of Ireland - says this is not the case.
We do not have a commercial partnership with Amazon and any Primark products which appear on the site are being re-sold by third parties, at higher prices. We encourage our customers to visit us in our stores to find the best value.
— Primark (@Primark) October 15, 2019
The products found on Amazon appear to be mainly limited to womenswear and its popular ranges of 'Disney' and 'Harry Potter' merchandise.
The prices being charged by independent sellers, in some cases, were almost double that of Penneys store price.
Customers responded to the company's tweet by suggesting that the retailer launch an online offering.
However, other users pointed out that such a move risked raising store prices as such a start-up would massively add to the company's costs.
The company, which opened its first store on Mary Street in Dublin back in 1969, marked its 50th anniversary earlier this year.
The firm has 372 stores in 12 countries, more than 75,000 employees and over 15 million sq. feet of retail space.
Primark opened its first UK shop back in 1973.
It then began expanding into Europe in 2006 - opening in Spain, followed by the Netherlands, Portugal, Germany, Belgium, Austria, France, the US and Italy.