The South Korean government has expressed condolences over the death of former North Korean hostage Otto Warmbier, urging Pyongyang to swiftly release all Americans and South Koreans detained in the North.

Warmbier died just days after North Korea transferred him to U.S. custody after apparently having been held secretly in a coma for more than a year. 

Foreign Ministry Spokesman Cho June-hyuck said Tuesday newly appointed Foreign Minister Kang Kyung-wha plans to express her own deep condolences soon in a scheduled telephone call with U.S. State Secretary Rex Tillerson. 

Cho added it is time for North Korea to return all detainees to their families.