The opposition has unilaterally passed a bill on a special counsel investigation into alleged state interference in probes into the death of a Marine last year.

The bill was approved Friday by the legislation and judiciary committee following the opposition's unilateral convening of a hearing on the bill during a plenary session, just nine days after it was submitted to the committee amid a boycott by the ruling People Power Party(PPP).

The initial bill, which was scrapped after a presidential veto under the previous 21st National Assembly, was resubmitted by the main opposition Democratic Party after a revision.

The new bill stipulates that the 70-day probe can begin early, during a 20-day preparation period, after which it can be extended by up to 60 more days.

The bill is set to be put to a vote at a parliamentary plenary session likely to be held in early July.