State prosecutors on Tuesday said they have indicted a local civic group chief on charges of carrying out an illegal protest against a controversial deal reached by Seoul and Tokyo on former sex slaves last year.

The Seoul Central District Prosecutors' Office said the defendant, identified only by her surname Kim, is accused of unlawfully entering the building where the Japanese Embassy is located in central Seoul in December.

Prosecutors said the 24-year-old defendant allegedly occupied the hallway on the second floor of the building for about an hour with some 30 other students while chanting against the deal. The embassy is located on floors eighth through eleventh.

On Dec. 28, South Korea and Japan reached a landmark deal in which Tokyo apologized for its colonial-era atrocities and agreed to provide 1 billion yen ($9.4 million) for the creation of a foundation aimed at supporting the victims sexually abused by Japanese soldiers.

The deal has been hailed by the international community as a step in the right direction given that the issue has been a long-standing obstacle to ties between the two neighboring countries.

Still, some victims and liberal civic groups have accused the government of striking the deal without getting Japan's acknowledgment of legal responsibility nor consulting with the victims in advance.

Historians estimate that up to 200,000 women, mostly from Korea, were forced to work in front-line brothels for Japanese troops during World War II. (Yonhap)