Customs in Chengdu, capital of southwest China's Sichuan province, seize four containers of big black and brown beetles posted from Germany on May 16, 2016. [Photo: Chinanews.com]

Four containers of big black and brown beetles posted from Germany have been seized by customs officers in Chengdu, the capital of southwest China's Sichuan Province.

The West China Metropolis Daily quotes customs officials as saying that the insects are smelly and three times larger than regular black beetles.

Experts are now inspecting the insects to identify the species and whether they might spread disease.

One month ago, a package with more than one hundred ants inside was discovered by Chengdu customs officers. In Beijing, the inspection and quarantine bureau officers seized ten arrow-poison frogs, one of the nature's deadliest creatures.

By law, any animals, plants or their products must be declared to Chinese customs, with the correct import and export certificates supplied. Customs officials say there is a danger that imported animals and plants could damage the delicate balance of the local eco-system and have an effect on the environment, economy and people's health.