Two former National Intelligence Service chiefs of the Park Geun-hye administration were arrested Friday in the expanding probe into allegations that several billion won of NIS funds were funneled to the presidential office.

The Seoul District Court approved arrest warrants for the two former NIS chiefs Nam Jae-joon and Lee Byung-kee over separate charges of embezzlement and bribery.

Prosecutors had sought warrants for the two and another former NIS head Lee Byung-ho, claiming the three had given a total of 4 billion won ($3.6 million) to senior presidential aides.

But the court did not grant the warrant for Lee Byung-ho as it saw the accused as not presenting any risk of flight or destruction of evidence.

The three led the nation’s spy agency from 2013 to 2017 under jailed former President Park Geun-hye. They are suspected of regularly channeling funds to Park and the presidential office. Prosecutors believe the money was used for illegal political activities and also for personal use.

While admitting that they had handed over large sums to presidential aides on a monthly basis, the three claimed they did so upon the request of Cheong Wa Dae and that they could not deny the presidential office.

Lee Byung-ho, who has not been arrested, was the last chief to serve under the former government. It is believed that the largest sum -- 2 billion won -- was given to presidential aides during his term from March 2015 to June this year. But he maintained that he was simply following the custom that had begun before he was appointed.

Nam was in office from March 2013 to May 2014, while Lee Byung-kee worked from July 2014 to February the following year.

The money came from the intelligence agency’s allotted budget dubbed as the “special activities fund” and it was given regularly to presidential aides with close ties to Park. According to prosecutors, the practice is likely to have been started by Nam.

The special activities fund is said to be over 500 billion won each year. But the NIS is not required to disclose how the money is spent. It is not audited or scrutinized by the National Assembly, as the budget is intended to finance the most covert operations that require confidentiality.

Prosecutors are also looking into the possibility of lawmakers close to the former conservative leader receiving bribes from the spy agency.

It has been alleged that Park loyalist and conservative heavyweight Rep. Choi Kyung-hwan of the main opposition Liberty Korea Party received 100 million won from the NIS. Choi, a four-term lawmaker, served as deputy prime minister for economy in 2014. Choi has denied the allegations.

The report comes a day after incumbent NIS chief Suh Hoon told the parliamentary intelligence committee that he did not confirm reports that a number of lawmakers also received money from the NIS.

During the intelligence committee meeting, chief lawmaker Rep. Kim Byung-kee said the National Assembly will start looking thoroughly into the details of the agency’s budget use.

By Jo He-rim (herim@heraldcorp.com)