Police and customs officials in Hai Phong on Thursday found 15 containers of plastic scrap mixed with a lot of industrial toxins.
The containers had been left at the Doan Xa Port in the city unclaimed since March.
The receiver, Que Thanh Import Export Commerce Joint Stock Company from neighboring Quang Ninh Province, sent a note refusing to collect the containers.
Authorities are testing the containers. Information about where the waste was imported from where and by whom has not been made available.
Hai Phong police last month reported two similar cases in which nine containers of plastic waste was found mixed with harmful residues and the stated recipients refused to accept them.