Three opposition parties on Monday approved details of a parliamentary probe into the deadly Itaewon crowd crush, without the participation of the ruling People Power Party(PPP).

The main opposition Democratic Party(DP), the Justice Party and the Basic Income Party convened the special committee on the investigation, agreeing on a list of witnesses, as well as two rounds of on-site visits, two rounds of briefings by related ministries and a three-day hearing.

The on-site investigations will include the site of the tragedy, the Itaewon police substation, the Seoul Metropolitan Police Agency, the Yongsan district office and the interior ministry, which will be conducted on Wednesday and Friday.

Eight government ministries, including the Prime Minister's Office, will be called to give briefings on December 27, and another group of ten public offices, including the Seoul city government, on December 29.

The three-day hearing is set to be held on January 2, 4, and 6, with the list of witnesses to be finalized through negotiation with the PPP.

The list of 44 witnesses approved on Monday include interior minister Lee Sang-min, National Police Agency Commissioner General Yoon Hee-keun, and Han Oh-seop, the chief of the presidential office's situation room for state affairs.

The PPP boycotted Monday's proceedings and accused the DP of breaking an earlier agreement to handle details of the probe after passing next year's budget bill.