The presidential office called Sunday for the swift passage of a controversial bill to reform the public employee pension system as the National Assembly is set to open an extra session this week.

The bill to restructure the debt-ridden pension plan for government employees has been at the center of the Park Geun-hye government's recent reform drive.

The much-awaited passage of the bill, however, fell apart in parliament on the last day of the preceding extra parliamentary session last week as rival parties failed to reach an agreement on the conditions of the bill's passing.

The main opposition New Politics Alliance for Democracy (NPAD) had initially agreed to pass the bill on the condition that the benefit from the overall national pension plan be increased to cover 50 percent of pre-retirement income from the previous 40 percent.

The ruling Saenuri Party's last-minute rejection of the proposal led to the parliamentary impasse.

"The top priority should be put on processing the public worker pension (bill) that is adjusted to the citizens' expectations. The passage should be carried out in the National Assembly without fail in May," chief presidential press secretary Kim Sung-woo said in a press briefing.

The presidential official said the national pension issue should be negotiated separately without being linked to the public worker pension issue at hand.

"It is not desirable to tie the national pension to the civil servant pension because the issues of the income replacement rate and the insurance rate increase need prior agreement from the citizens," Kim noted.

He also took issue with the opposition proposal, saying that the increase of the income replacement rate to 50 percent will require an input of 1,702 trillion won in taxpayers' money over the following 65 years.

"An increase of even one percentage point (in the income replacement rate) may pass a disastrous burden on to future generations," Kim said.

The call on the parliament came as rival parties are set to meet again starting Monday for a one-month extra parliamentary session, which was called after the previous extra session ended without success.

The civil servant pension issue is expected to dominate the coming session again although the prospect of the bill's passage is unclear with both parties still wrangling over it. (Yonhap)