Prosecutors on Tuesday detained two former secretaries of ousted President Park Geun-hye over allegations that they took bribes from state spy agency officials.

Ahn Bong-geun and Lee Jae-man, the closest aides to Park, were taken into custody on an urgent warrant approved by a court, the Seoul Central District Prosecutors' Office said.

They are suspected of regularly receiving money from then National Intelligence Service officials when they worked at Cheong Wa Dae between 2013 and 2016.

Ahn served as Park's personal aide and communications secretary, and Lee was in charge of general affairs of the presidential secretariat. 

Lee Hun-soo, a former senior NIS official, reportedly confessed the alleged bribery to the prosecution  during an earlier interrogation. He was being questioned over his involvement in the spy agency's alleged political interference under the two previous administrations.

"This is a bribery case, in which then top Cheong Wa Dae officials are suspected of taking bribes from NIS staff," the prosecution said. 

The prosecution suspects some 4 billion won ($3.56 million) from NIS special activities expenses were funneled into the presidential office at that time.

Also on Tuesday, the prosecution investigators raided some 10 locations including the residences of three former NIS chiefs, former Culture Minister Cho Yoon-sun and the two presidential aides.

Cho, who has already been on trial for illicit management of a government blacklist of media and cultural figures, is suspected of being involved in the fresh bribery allegations, it said.

Prosecutors said they have put travel bans on those involved and plan to soon summon more suspects for questioning.

 The two ex-Cheong Wa Dae secretaries, along with the now-jailed former presidential secretary Jeong Ho-seong, have been dubbed the "doorknob trio," due to their close ties with Park. (Yonhap)