Unionized public workers and teachers vowed Saturday to fight vigorously against a proposed pension reform bill now before the National Assembly for approval, arguing that it is unfairly disadvantageous to them.

After months of negotiations, rival parties agreed on a bill Friday that would require civil servants to pay more into and receive less in pension over the next two decades. Reform of the money-losing public servants' pension system is one of President Park Geun-hye's key campaign pledges.

Drafted by a task force of government officials and experts, the bill calls for raising contribution rates from current 7 percent to 9 percent over the next five years while lowering the payment rates from current 1.9 percent to 1.7 percent over the next 20 years.

Should it be approved by a bipartisan special parliamentary committee, the bill is expected to pass through the main floor session next week, according to officials from the ruling Saenuri Party and the main opposition New Politics Alliance for Democracy.

"We have never agreed to the proposed plan to change the contribution rate to 1.7 percent and the payments to 9 percent and any other changes," the Korean Government Employees' Union said in a statement. "We cannot accept the proposal that would worsen the current pension system."

The public workers' union vowed an "all-out struggle" against the reform bill even if it is adopted by the National Assembly.

A major teachers' union also voiced their opposition to the new plan.

"We, by all means, will prevent the evil pension bill which some members of a teachers' union and a public workers' union agreed to without any authority to do so. It also is a result of collusion between the rival parties," the Korean Teachers and Educational Workers' Union said in a statement.

(Yonhap)