Unionized government workers vowed Thursday to hold a mass rally later this week to protest the government's proposal to scale back a pension program for its employees starting 2016.

The Korean Government Employees' Union said more than 120,000 people from 50 related unions were expected to attend the rally scheduled for Saturday in southern Seoul.

Rosa Pavanelli, general secretary of Public Services International, is scheduled to give a speech at the event, the union added.

The move comes after the government revealed a draft bill earlier this month that will start requiring its workers to pay more into and receive less pension in 2016.

The bill is part of a government plan to undercut its growing pension deficit, which is forecast to reach 484 trillion won (US$458 billion) if left unaddressed.

Government workers, however, have rejected the proposal, saying they have tolerated low pay for a promise of high returns after retirement.

The coalition of related unions said it will take a vote at Saturday's rally to determine whether to stage a general strike sometime later.

Speaking at the National Assembly on Wednesday, President Park Geun-hye asked civil servants to make concessions and sacrifices for future generations and the country, saying the pension deficit is feared to snowball in coming years unless the pension plan is reformed. (Yonhap)