A defector-turned-official working for the Seoul Metropolitan Government was indicted Tuesday on charges of carrying out espionage activities for the communist regime, prosecutors said.

The 33-year-old spy, only identified as his surname Yoo, is accused of handing over the information of some 200 defectors living in Seoul to Pyongyang's spy agency, they said.

The suspect, who has a Chinese nationality, arrived in South Korea in 2004, disguising himself as a North Korean defector, they said. In 2011, he was hired by the Seoul Metropolitan Government as a two-year contract official.

Most of the information on the defectors was allegedly gathered through his contact with local defectors' groups, they said.

However, the information of up to 60 defectors was collected while he was working for the city government.

Yoo allegedly gave the detailed information on the defectors to his sister when he visited the North illegally on a Chinese passport before she passed it on to Pyongyang's National Security Agency there, they added.

"North Korea's espionage activities have diversified by infiltrating spies from different classes," a prosecution official said.

The probe comes after his sister was detained last year by Seoul authorities when she was trying to defect to South by posing as a defector, they said.

Prosecutors said they will further investigate into the sister and later decide whether to bring charges against her.

South Korea is currently home to more than 24,000 North Korean defectors. (Yonhap News)