"I don't think it's enough anymore to say 'We're not involved in these particular factories,'" Sapriel said.
Many clothing brands were quick to distance themselves from the five factories that were housed in Rana Plaza. The building, which was not designed for industrial use and had three illegally added levels, collapsed April 24.
Benetton said none of the factories were its authorized suppliers, although Benetton labels were found in the rubble. Spain's Mango said it hadn't bought clothing from Rana Plaza factories but acknowledged it had been in talks with one factory to produce a test batch of clothing.
German clothing company KiK said it was "surprised, shocked and appalled" to learn its T-shirts and tops were found in the rubble. The company said it stopped doing business with the Rana Plaza factories in 2008. It promised an investigation.
Wal-Mart said there was no authorized production of its clothing lines at Rana Plaza but it was investigating whether there was unapproved subcontracting. Swedish retailer H&M, the single largest customer of Bangladeshi garment factories, said none of its clothes were produced there.
The Walt Disney Co. in March responded to publicity from last year's fire at the Tazreen factory, where its branded clothing was found, by pulling out of Bangladesh production altogether.