The union has been claiming that the shareholders' meeting in Ulsan on May 31 didn't follow the proper steps and thus the decision made there should be nullified.

In March, Hyundai Heavy signed a formal deal, worth an estimated 2 trillion won ($1.7 billion), with the state-run Korea Development Bank to buy Daewoo Shipbuilding. The bank is the largest shareholder of Daewoo Shipbuilding, with a controlling 55.7 percent stake in the company.

Under the deal, the company was split into Korea Shipbuilding & Offshore Engineering Co. and a reorganized Hyundai Heavy Industries.

The unionized workers have been opposing the plan, claiming it jeopardizes their job security. (Yonhap)