Arrest warrants have been issued for two South Korean army colonels allegedly involved in clandestine political cyber-operations under the administration of former president Lee Myung-bak, who was himself arrested on corruption charges on Thursday.

The two colonels, who have not been named, were indicted on Tuesday for an operation that sought to manipulate public opinion on sensitive political issues by posting online comments on news sites in support of Lee Myung-bak’s government and attacking its critics.

The defence ministry announced South Korea’s military court had issued the warrants alleging the colonels ran a secret team, known as Sparta, during Lee’s presidential rein from 2008 to 2013.

According to investigators, issues targeted by the team included the controversial Jeju naval base, the construction of which was opposed by local protesters, leading to work being delayed seven times between 2007 and 2011. Opponents claimed the US was behind the project and that the base was being built in response to China’s growing military strength rather than to boost South Korea’s defence.

The team is also accused of attempting to sway opinion on the South Korea-US trade agreement, recently renegotiated after President Trump’s plans for imposing steel and aluminium tariffs, and the sinking of the ROKS Cheonan naval vessel by North Korea, which led to the deaths of 46 South Korean sailors.

Lee, 76, is being held on a string of corruption charges including bribery, abuse of power and election law violation. He is alleged to have taken millions of dollars in bribes from individuals and organisations, including from the South Korean intelligence services.

The conservative former president refused to be questioned by prosecutors on Monday at the Seoul detention centre where he is being held, claiming the charges were politically motivated and he would be unable to get a fair trial.

Park Geun-hye, the conservative president who succeeded Lee, was also arrested last year on charges of massive corruption and is being held in detention, facing the prospect of up to 30 years in prison.