The passage of an anti-terrorism bill has been thrown into doubt as opposition lawmakers staged a marathon filibuster for the second straight day Thursday.

The bill, which was forcibly taken by the assembly speaker to the floor for a vote late Tuesday, has been stalled by the delaying tactics of several lawmakers from the main opposition Minjoo Party and two other minor opposition parties.

A similar bill was introduced by then-liberal government at the National Assembly following the Sept. 11 attacks in 2001 to combat possible terrorism in South Korea, though no major progress was made.

The anti-terrorism bill has recently gained new momentum in South Korea as North Korean leader Kim Jong-un has ordered officials to concentrate on building capabilities for terror attacks and cyberattacks on South Korea.

Tensions have spiked on the Korean Peninsula over North Korea's recent nuclear test and long-range rocket launch.

In the bill, an anti-terrorism center will be set up under the Prime Minister's Office, but the country's main intelligence agency, the National Intelligence Service (NIS), will have the power to gather relevant intelligence on possible terrorists and attacks.

At the center of dispute over the pending bill is whether to empower the NIS to pursue suspected terrorists by granting the agency with far-reaching authority permission to keep track of suspected terrorists

Under the proposed bill, the NIS will have the power to look into financial transactions and demand South Korea's financial regulator suspend financial services for anyone suspected of being a terrorist.

The intelligence agency will also have power to keep track of locations of suspected terrorists and look into their immigration records. Under the bill, provision two of the article nine, the NIS will be capable of tapping into phone conversations as well.

The opposition has demanded that the article be taken out of the law, citing possible power abuse by the NIS to suppress political dissidents.

To persuade the opposition, the Saenuri made some changes in the bill, requiring the NIS to report to the Prime Minister's Office before or after it exercises its power of pursuit.

The revision also stipulates that the anti-terrorism center have one human rights official to monitor for possible breach of such rights during the process of pursuit.

The Minjoo Party, however, disapproves of the revised bill and insists that Article 9 be discarded while the Saenuri says taking out Article 9 neutralizes the anti-terror capabilities intended by the law.

Technically, the opposition lawmakers can continue the delaying tactics until March 22, when the session is scheduled to wrap up.

Political analysts, however, say that the filibuster is likely to end on Friday when the rival parties agree to put an electoral map for April's general elections to a vote.

If the anti-terrorism bill were put to a vote following the end of filibuster, it is most likely to pass as the Saenuri controls 157 seats in the 293-member National Assembly.