An Australian student in Pyongyang was detained for spying last month and admitted his "anti-state" activities, the North Korean state media said Saturday, two days after his expulsion from the communist nation.

Alek Sigley, a 29-year-old university student in Pyongyang, was reported missing in late June, but he was released on Thursday and left the North Korean capital the same day.

The Korean Central News Agency (KCNA) said the Australian had passed on data and photos on domestic situation to "the NK News and other anti-DPRK media" and was caught by the North Korean authorities on June 25.

"Alek Sigley was caught red-handed committing anti-DPRK incitement through internet," the Korean Central News Agency (KCNA) said in an English report, using the abbreviation for the country's formal name, the Democratic People's Republic of Korea.

Siely admitted "his spying acts of systematically collecting and offering data about the domestic situation of the DPRK" and repeatedly asked for pardon, KCNA said.

Sigley had been pursuing a master's degree in North Korean literature at Kim ll-sung University and running a tourism company in Pyongyang. (Yonhap)