China Post offered to help investigate the origin of the strange seed packets sent to the American mailboxes.

"China Post has proposed to the US Postal Department to return these fake packages to China for investigation," Chinese Foreign Minister Wang Wen Bin said on July 28.

Wang said the information on the packages' labels seemed to be faked, after checking by China Post, adding that there were many errors in the package attachment information.

People in many US states have reported receiving unknown shippers from China, symbolized as toys or jewelry.

Agricultural officials in at least 27 states in the US have warned people not to plant strange seeds and contact the government if they receive the seeds.

The Virginia Department of Agriculture is one of several agencies warning that they may contain invasive species "that devastate the environment, replace or destroy native plants and insects, causing heavy crop damage".

However, the police department in Whitehouse, Ohio, thinks this could be a scam in which the seller sends the recipient the item they did not order, then impersonates "authenticated buyer".