Rival political parties failed Wednesday to make progress in talks to begin a parliamentary investigation into last month’s deadly ferry sinking.

The investigation, which had been scheduled to start Tuesday, has been delayed due to wrangling between rival parties over whether to include specific names of witnesses in a joint proposal for the probe.

The main opposition New Politics Alliance for Democracy has especially demanded the inclusion of presidential chief of staff Kim Ki-choon, but the ruling Saenuri Party has insisted that the selection of witnesses be left to a special parliamentary committee handling the investigation.

“(The opposition party) wants to ignore the law and include specific witnesses,” Rep. Lee One-koo, the floor leader of the ruling party, said during a party meeting. “We can’t break the law in the process.”

The opposition party accused the ruling party of trying to protect the presidential chief of staff.

“The Saenuri Party fell to their knees during the talks at the name of presidential chief of staff Kim Ki-choon,” Rep. Park Young-sun, the NPAD floor leader, said during a party meeting.

Meanwhile, family members of those who died in the sinking held a press conference at the National Assembly demanding the parties immediately reach an agreement and begin the investigation.

More than 30 family members have camped at the National Assembly since Tuesday in protest of the parliamentary deadlock.

The 6,825-ton Sewol sank off the country’s southwest coast on April 16, leaving more than 300 people dead or missing. Most of the victims were students from a high school near Seoul on a field trip to the southern resort island of Jeju. (Yonhap)