SYDNEY, Australia — An Australian student at a North Korean university whose family lost contact with him last week was freed from detention on Thursday by the North after Swedish officials took up his plight with Kim Jong-un’s government.

Fears about the fate of Alek Sigley, 29, who was pursuing a master’s degree in Korean literature at Kim Il-sung University in Pyongyang, had grown after he went silent on social media on June 25 and the North Korean government said nothing publicly about him.

His family, working with Australian officials, had been urgently seeking information about his whereabouts and welfare. After South Korean news outlets, citing anonymous sources, reported that Mr. Sigley had been detained, there were worries that he might be facing harsh conditions in the North’s prison system. In 2017, an American student, Otto F. Warmbier, died after falling into a coma while being detained in North Korea.

But on Thursday, Mr. Sigley emerged at Beijing’s international airport smiling and saying, “I’m O.K., I’m good,” while declining to address a reporter’s question about why he had been detained.