Jakarta. Police have extended Kivlan Zen's detention for another 20 days on Thursday after declaring him a suspect in the assassination plot against four high-ranking officials and the head of a polling agency, one of his lawyers said.

The former chief of staff of the Army's Strategic Command (Kostrad) was earlier also declared a suspect in another case involving treason allegations.

"It is linked to the illegal possession and use of lethal weapons. This is based on [testimony by] a suspect, Mr. Kurniawan, alias Iwan, and his friends," Djudju Purwantoro, the coordinator of Kivlan's legal team, said as quoted by Antara news agency.

Police have arrested six suspects, only identified by the initials H.K., A.Z., I.F., T.J., A.D., and A.F., on May 21 and 24, and seized at least four firearms in various locations in Jakarta, West Java and Banten.

According to police, the six suspects were allegedly involved in a plot to assassinate Chief Security Minster Wiranto, Coordinating Maritime Affairs Minister Luhut Pandjaitan, State Intelligence Agency (BIN) head Budi Gunawan, Gories Mere (a special staffer for intelligence and security in the office of the president), and the head of a polling agency, whom they chose not to identify.

Police said the suspect H.K., also known as Iwan, was a field operative and received orders from someone else to arrange and execute the plot.

Meanwhile, Djudju identified one of the six suspects as Armi, a part-time driver for Kivlan.

"Armi just worked part-time for Mr. Kivlan Zen – about three months – and [he] is one of the people declared a suspect for illegal possession of firearms. Therefore, Mr. Kivlan's [legal] status was upgraded this evening to that of a suspect, although he did not illegally possess a weapon," Djudju said.

Kivlan's legal team requested a postponement of his interrogation session scheduled for Thursday evening, due to poor health. He had been questioned for about 28 hours since Wednesday afternoon.

Police moved Kivlan to the detention barracks of the Military Police in South Jakarta on Thursday evening.

Djudju said the legal team plans to file a pretrial motion in a district court on Friday to seek the suspension of Kivlan's detention.

The retired general is detained under the 1951 Emergency Law and faces life imprisonment, if found guilty.