The National Assembly's regular parliamentary session kicked off Monday amid a political deadlock over April's deadly ferry sinking that claimed the lives of more than 300 people, mostly high school students.

The dispute between the nation's rival political parties -- the ruling Saenuri Party and the No. 1 opposition New Politics Alliance for Democracy  -- centers on a bill aimed at uncovering the truth behind one of the country's deadliest maritime accidents.

The 6,825-ton ferry Sewol capsized off South Korea's southwest coast on April 16, leaving 304 people dead or missing. The tragedy has become a political football as critics argue that the government's initial failure to properly respond to the disaster contributed to the high death toll.

Among other things, the bill calls for an independent investigation into the disaster through an ad hoc investigative committee and a separate independent counsel.

The victims' families have demanded that the investigative committee be given the right to investigate and indict those responsible for the tragedy. The ruling party has rejected the call on the grounds that it could disrupt the judicial system.

The opposition party has boycotted the passage of all other bills until after the ferry bill is endorsed by the parliament, disrupting all parliamentary proceedings, including the annual audit of the government, which was scheduled to begin last month.

"The Saenuri Party, together with NPAD, will create a special law that embodies the lesson of the Sewol," Rep. Lee One-koo, the floor leader of the ruling party, said during a party meeting.

"Trusting this, the regular parliamentary session must be normalized."

Rep. Park Young-sun, the NPAD floor leader, urged the ruling party to resolve the impasse.

"I ask the ruling party to demonstrate the minimum level of responsibility it should have as the ruling party," she said in a party meeting.

Over the next 100 days, the National Assembly is supposed to pass next year's budget bill, a set of pending bills, including those aimed at reviving the country's sluggish economy, and conduct the annual parliamentary audit of the government.

On Monday, an arrest motion against Rep. Song Kwang-ho of the ruling party was brought to the floor.

Song is accused of taking bribes worth 55 million won ($54,000) from local railway parts supplier AVT in return for business favors.

His arrest is subject to parliamentary consent as lawmakers in South Korea are immune from detention while the National Assembly is in session.

Under parliamentary law, the arrest motion must be put to a vote within 72 hours, but not within the first 24 hours. Majority approval is required for the motion to pass.

The rival parties agreed to put the motion to a vote during a plenary session on Wednesday.

Also Monday, the Saenuri Party held its third meeting with the victims' families to try to resolve the deadlock over the ferry bill, but no progress was made, both sides said. (Yonhap)