Police have yet to confirm the presence of chemical substances in over two-thousand suspicious international deliveries reported from around the country in the past several days.

Police Commissioner General Yoon Hee-keun said on Monday that the Agency for Defense Development found no toxicity in the first parcel reported in the southeastern city of Ulsan after its recipients claimed to experience symptoms of paralysis.

While the National Forensic Service is conducting a second-phase test of the Ulsan parcel, the police chief said toxic substances have not been neither reported nor confirmed in any other cases.

Yoon said the police are also looking into the possibility of a "brushing scam" in which businesses send parcels to people containing items they have not ordered as a marketing strategy, with a possible legal review for criminal punishment.

He said Seoul has also sought cooperation from the Chinese public security ministry through Interpol.

According to the police, as of 5 a.m. Monday, they have received reports of two-thousand-141 suspicious international deliveries since a package suspected of containing hazardous substances arrived at a welfare center in Ulsan last Thursday.