Opposition parties approved through a parliamentary subcommittee a bill on a special counsel investigation into the December 3 martial law decree that stipulates special prosecutor recommendation from outside the National Assembly.

The bill, which passed a subcommittee of the Legislation and Judiciary Committee Friday, gives the recommendation authority to the Supreme Court chief justice, while removing the opposition's veto right, in response to protests from the ruling People Power Party(PPP).

The number of investigators was reduced from 205 to 155, and the probe was shortened from 170 days to 150 days.

The opposition bloc led by the main opposition Democratic Party(DP) introduced the revised bill on Thursday, after an earlier version was vetoed by acting President Choi Sang-mok, then voted down in a second plenary vote.

The ruling party, meanwhile, boycotted Friday's vote in protest of the opposition's unilateral handling of the bill, saying it lacked enough time for deliberation.

The bill authorizes the special prosecutor to look into allegations of treason, defined as jeopardizing national security by conspiring with a foreign state, standing up against one’s country, or providing benefits to an enemy state.

After passing the standing committee on Monday, the bill is expected to be put to a vote at a plenary session later in the week.