Spokeswoman Marta Soler Morera said the orders — placed between January and March for leggings, T-shirts and polo shirts according to documents seen by AFP — were "only for sample items".
She added in an email to AFP that "25,000 items are not a lot for a sample order for various lines of the brand" which is sold in 2,600 shops worldwide in 109 countries.
The manufacturer, Phantom-TAC, "is not an official supplier of Mango" and had not yet been fully audited, she said.
Only British low-cost fashion line Primark has acknowledged having its products made in the factory bloc, which imploded on Wednesday morning raising further concern about safety and working conditions in Bangladesh.
The Bangladesh Garment & Industrial Workers Federation said its activists had collected labels for the Tex brand belonging to French supermarket Carrefour, but the company denied having an official supplier in the building.
"A deeper investigation, started immediately, is under way," the company said.
The federation also provided production documents relating to orders by Benetton to New Wave Style, but the Italian label said "people involved in the collapse of the factory in Bangladesh were not Benetton Group's suppliers".
The Clean Clothes Campaign pressure group said labels linking European retailer C&A to the accident were also found at the scene. The group told AFP it had terminated its links with a manufacturer in the building in 2011.
Wal-Mart said it was investigating whether its clothes were being made in the now destroyed Rana Plaza, where thousands of relatives gathered Thursday hoping for news of their missing loved ones.
In November, the US giant admitted that its products were found at a factory were 111 people died in the local industry's worst fire, but it said the work had been sub-contracted without authorization by one of its official suppliers.
Such unofficial "outsourcing" is common in the industry where manufacturers face immense pressure from retailers to cut prices and deliver on time, say activists.
C&A and Hong Kong supplier Li & Fung confirmed they also had clothes cut at the factory.