A trio of opposition parties will request a parliamentary investigation into the cause of the horrific Itaewon crowd crush that killed more than 150 people.

The main Democratic Party(DP), the Justice Party and the Basic Income Party will likely be joined by a group of independent lawmakers that had defected from the DP in submitting the request Wednesday afternoon.

The DP, which has criticized the National Police Agency for leading the investigation into the agency’s response to the crush widely considered deficient, plans to report the parliamentary probe request during Thursday's plenary session.

Once the request is reported, the National Assembly speaker is able to form a special committee through consultation with the heads of negotiation groups.

The ruling People Power Party(PPP), for its part, opposes the parliamentary probe at this time, saying priority should be given to the outcome of the police investigation.