Samsung and SK, South Korea's two largest conglomerates, are believed to have provided some 2 billion won ($1.77 million) to a number of conservative activist groups at the request of the spy agency under the Lee Myung-bak government, prosecution sources said Tuesday.

The investigation team at the Seoul Central District Prosecutors' Office has reportedly figured out the amount of contributions based on recent interrogations of the people involved, the sources said.

The team has taken charge of a broader probe into alleged political interference by the National Intelligence Agency during the previous governments led by then-Presidents Lee Myung-bak and Park Geun-hye. 

The NIS is accused of running a series of secret operations online and offline intended to benefit the two conservative governments, while maligning their political opponents or those critical of their policies.

Suspicions have risen that the spy agency had big conglomerates pay right-wing activist groups large sums of money for support.

The spy agency is suspected of using key business lobbying groups as a channel for the implicit transfer of payments. An internal NIS task force has found some 11.8 billion won in funds were paid to conservative organizations between 2010 and 2012 to stage pro-government rallies and a campaign against the liberal bloc.

Prosecutors are apparently set to file for an arrest warrant for a former NIS unit chief over a suspected role in arranging the illicit funding. (Yonhap)