President Park Geun-hye ruled out concessions on Tuesday as she urged the parliament to quickly pass a contentious bill meant to uncover the truth behind April's ferry disaster.

She has been under pressure to allow a proposed ad hoc committee for an independent probe into the ferry sinking to have the right to investigate and indict those responsible for the tragedy, a key demand by the families of the ferry victims.

"The call is not something that she can determine as the president as it would undermine the separation of powers and the judicial system," Park said in a Cabinet meeting.

Her comments came as there was no end in sight to weeks of political deadlock between the rival parties over the bill on the ferry sinking that left more than 300 people dead.

The main opposition New Politics Alliance for Democracy has vowed to boycott the passage of all other bills until the ferry bill is endorsed by the parliament.

The political row has disrupted parliamentary proceedings, leaving a set of bills meant to revitalize the economy and lift regulations in limbo in the parliament. (Yonhap)