The state intelligence agency on Wednesday raided the homes and offices of several officials of a minor progressive party over an alleged security law breach, prosecutors said.

With a court-issued warrant, the National Intelligence Service (NIS) agents began searching the homes and offices of 10 officials and lawmakers of the Unified Progressive Party (UPP) including Rep. Lee Seok-ki, they said.

"(The UPP officials) are charged with conspiracy to stage a rebellion and violating the National Security Law," said Choi Tae-won, a senior prosecutor of the Suwon District Prosecutors' Office.

"The NIS has long prepared an internal investigation into the case," Choi said, declining to further comment on detailed charges as the investigation is ongoing.

The draconian law has long been a politically controversial issue. Enacted in 1948 to fight communism, the law bans any activity that "instigates rebellion against the state."

The UPP criticized the NIS' move, saying that the spy agency is abusing its political power instead of apologizing for allegedly meddling in last year's presidential election. (Yonhap News)