Fishermen in some localities in the Vietnamese central province of Thanh Hoa have found about 100 bags containing unidentified substance with foul smell drifted ashore from unknown location over the last few days, local authorities reported Friday.

These strange bags were spotted along the beaches in Sam Son Town and two districts of Quang Xuong and Hoang Hoa, according to officials.

In Sam Son, about 50 bags were collected while around 30 and 15 bags were found in the above districts, respectively. These bags have many Chinese characters on them, but most of them were too blurred to see, except for two big words “Feng Yuan" in blue, according to the People’s Committee of Sam Son town. There is also a dim round logo below these two words, the committee said. These sacks contained an unknown type of clotted powder that produced stinking odor, some fishermen who had opened the bags said. Local authorities, in conjunction with police and border guard forces, have gathered all of the sacks in one place and buried them underground. Thanh Hoa police have taken samples of the substance and sent them to a competent agency for testing.  According to some fishermen, the strange matter may derive from a kind of seawood.