The foreign ministry has requested cooperation from China in relation to suspicious international packages delivered across South Korea over the past few days. 

Seoul’s foreign ministry said on Sunday that it contacted the Chinese foreign ministry as well as relevant authorities and local governments through South Korean diplomatic missions in the country and requested a swift confirmation and explanation of the deliveries.

The ministry said that the Chinese side expressed its intent to fully cooperate with the request. 

The ministry added that it plans to study similar cases in other countries, such as Canada and the United States, and how they were handled.

In addition, a warning was also issued for South Koreans abroad to pay attention to international packages, while instructing all diplomatic missions to strengthen delivery security.

The string of incidents began when a package suspected of containing hazardous substances arrived at a welfare center in Ulsan on Thursday, prompting recipients of similar deliveries across the country to report them.