Seoul: Tens of thousands of South Korean auto and shipbuilding workers are set to launch partial strikes this week after negotiations over wage increases stalled.

Employees at Hyundai Motor — the South’s top automaker — are set to walk off the job for at least four hours a day from Tuesday to Friday, a labour union spokesman told AFP.

About 75 percent of the firm’s 48,800 unionised workers voted last week for the stoppages after months-long negotiations with management failed to meet their demand for a 7.2-percent pay rise and other benefits.

It would mark the fifth straight year of industrial action at the automaker. Hyundai, along with its smaller affiliate Kia, forms the world’s fifth-largest carmaking group.

At the same time, workers at Hyundai Heavy Industries — the world’s largest shipbuilder by sales — are set to walk off the job for at least four hours a day on Tuesday, Wednesday and Friday.

Some 60 per cent of the 15,000 unionised workers approved the partial stoppage to demand a bigger wage rise and bonuses.

Workers of the two firms will hold a joint rally Wednesday in the southeastern industrial city of Ulsan, where both companies have their biggest plants, a Hyundai Heavy union spokesman said.

‘We happened to go on strike at the same time so we decided to do this together,’ he told AFP.

It will be the first time in 23 years that workers in both firms have staged industrial action at the same time.

The planned strikes could cost both firms heavily. Hyundai Motor has suffered drops in quarterly profit for nearly two years due to slumping sales in China and currency swings.

Hyundai Heavy has been forced to shed thousands of jobs in recent years as part of state-led restructuring of the country’s once-mighty shipbuilding industry.

The Ulsan-based firm has reported a net loss for two straight years totalling $4.4 billion, after a prolonged slump in oil prices and the global economic slowdown sapped demand for tankers and container ships.

The South’s ‘Big Three’ shipbuilders — Hyundai, Samsung Heavy Industries and Daewoo Shipbuilding and Marine Engineering — have cut tens of thousands of jobs amid mounting losses, sparking angry protests from workers.