Union workers in the public sector held a massive rally in central Seoul on Thursday in protest of the government's push to expand a performance-based pay system, police said.

About 2,000 members of the Federation of Korean Public Industry Trade Unions gathered in front of Seoul Station, according to police. The number of participants that the rally organizer said took part in the event stood at around 5,000.

During the protest, the federation said its members will put utmost efforts towards preventing the government from introducing a performance-based wage system.

The wage system is part of the Park Geun-hye administration's efforts to boost labor flexibility to create more jobs, especially for the young generation.

Some 120 public companies and institutions are in the middle of adopting the new wage program, with some of their unions protesting the move.

"The lives of public sector workers have been pushed to the edge of a cliff by the violence committed under the name of reform in the last three and a half years," federation chief Kim Joo-young said.

Wednesday's rally marked the first of a series of similar ones scheduled to follow until the end of this month, including those from the country's financial and rail unions. (Yonhap)