Unionized sailors and other sea-based workers of South Korea's largest shipper HMM Co. have voted in favor of staging their first-ever strike after wage negotiations with the company reached a deadlock, industry sources said Monday.

Around 92 percent of the seafarers who have participated in the vote supported the proposed walkout, and they plan to hand in letters of resignation to the management Wednesday, according to the sources.

The union added it is still open to reach a last-minute agreement with the company, should the management come up with a sweetened proposal.

Union members demand an 8-percent pay increase on top of a bonus amounting to 800 percent of their wages. In contrast, the management offered workers an 8-percent raise, along with bonuses of 500 percent.

The company's land-based labor union is also considering launching an action as some 95 percent of unionized longshore workers voted against the wage proposal as well.

HMM posted record earnings over the April-June period on the back of rising freight costs. Its operating profit rose 10 times from a year earlier to about 1.4 trillion won ($1.19 billion) in the April-June period.

Union members claim they have been underpaid compared to workers at rival companies and their wages have been frozen for up to eight years.

Shares of HMM closed at 37,350 won on the main bourse Monday, down 2.23 percent from the previous session.

The Ministry of Oceans and Fisheries, meanwhile, said it plans to operate a special task force to brace for potential disruptions in the shipment of export goods following the potential strike. (Yonhap)