U.S. officials said Americans who report getting unsolicited parcels containing seeds purportedly coming from China may be the victims of a bogus online retail scheme called a "brushing scam."

Residents of roughly 12 U.S. states reported being sent suspicious packages containing dozens of seeds that seem to have come from China. The origins of the seeds are not yet known and receivers are advised by local authorities not to plant them as they could be of the invasive kind.

The seeds have no packaging or label that identifies their source or maker, and U.S. authorities have asked recipients to return them so they can be examined in case they are invasive. The seeds have found their way into mailboxes from Washington to Virginia.

Chinese authorities have asked for the mystery seeds to be returned for examination and denied any accountability for the packages, saying that China Post restricts seeds from conveyance through post.

The United States Department of Agriculture does not have any solid proof to say the packages are something other than a scam, where a seller sends unsolicited packages in order for them to post fake customer reviews on the internet and bolster sales, the department disclosed.

Canadian authorities have also noted there have been reports of its citizens getting unsolicited seed packets, echoing the USDA's warning not to plant them. Officials are not sure of the motive behind the unsolicited packages but suspect that they're part of an online scam.

The commissioner of the Texas Department of Agriculture, Sid Miller, said multiple packets of the mysterious seeds that have been sent to Texas were found to be gardening and agricultural seeds.

What worries local Texas authorities is that some of the seeds could be noxious weeds or other invasive species that could damage the state's agricultural system, he explained, pointing out that intentionally keeping or planting them would be against the law because they are an illegal product.

Most of the vendors involved are foreign third-party sellers on Amazon. According to Liz Johnson, an identity protection specialist and proprietor of Digital Bodyguard Co. brush scams are the latest identity fraud that people should be on the lookout for. 

China's foreign ministry disclosed Tuesday that the suspect packages have been forged and do not originate from the Asian country. China Post has talked to its U.S. counterparts with regards to returning parcels to the Asian country so it can conduct a thorough examination, Foreign Ministry spokesman Wang Wenbin said.