Unionized bus drivers in the South Korean capital of Seoul went on a general strike Thursday to demand a wage hike, halting the operation of nearly 98 percent of buses running across the capital, according to Yonhap News Agency.

In their last-minute wage negotiations conducted from Wednesday till early Thursday morning, the Seoul Bus Labor Union and their employers failed to strike a deal over the union's demand for a 12.7 percent increase in hourly wages.

The union, which has about 18,000 members at 65 companies, responded by pushing ahead with its threatened strike, affecting 7,210 intracity buses, which represent 97.6 percent of the capital's bus services.

The general strike, the first since 2012, was expected to cause massive passenger inconveniences in the morning rush hour. The city government, in response, increased subway operations for the morning and evening rush hours, while the city's 25 districts provided emergency free shuttle services.

The bus union has been demanding a 12.7 percent hike in hourly wages, citing the outflow of its workforce to nearby regions, but the employers' side dismissed it as "excessive," particularly in consideration of the inflation rate of the past five years.

The two sides planned to continue their negotiations for a breakthrough even after the strike was launched.