Unionized workers at Homeplus, the nation’s second-largest chain store owned by the U.K.’s Tesco, on Wednesday threatened to stage a strike from Jan. 9, calling for management to scrap the current half-hourly wage system.

Having already held partial strikes, the unionists called for an hourly basis payroll, which was adopted by other chain stores including E-Mart and Lotte Mart.

“The so-called half hourly payroll system is unheard of in the industry. Homeplus has been taking advantage of the system to pinch extra pennies,” the union said.

“We call for the management to renew contracts on an hourly-based system. If not, we have no choice but to stage a full strike,” it stated on Wednesday.

About 400 unionists at five branches in Busan and Ulsan conducted a partial walkout on Dec. 30. Aligned with consumer activists, they urged the public to boycott shopping at the retail store.

Homeplus, which marked 8.8 trillion won in sales between March 2012 and February 2013, established a new payroll system in 2004 with its irregular workers on a 30-minute basis instead of the conventional hourly system. Many of the workers now work four hours and 30 minutes, or seven hours and 30 minutes instead of six hours or eight, respectively.

About 15,000 irregular workers, accounting for 57 percent of the 26,000-strong workforce, are affected by the system.

The union has argued that the system was designed to take advantage of “an extra 30 minutes of labor.”

“For example, the cashiers need 20-30 minutes to handover their duties to their successor, which easily constitutes eight hours. This happens every day. The company has never offered compensation for the extra service,” the union said. Unionists revealed that the management has recently amended the payment to a 10-minute-based contract, creating four hours and 20 minute-, or six hours and 20 minute-working systems.

Homeplus refuted that the company has been in talks with workers over improving the contract system. Under the arbitration of the National Labor Relations Commission, the management offered an improvement plan to the union on Dec. 17, only to see it rejected. The details of the offer were undisclosed.

“It is not illegal to adopt a specified form of working hours for irregular workers,” said Kang Jong-ho, a Homeplus official. Kang said that working an extra 20-30 minutes a day is considered inevitable given the nature of the service industry.

“We understand that fewer than 1,500 workers are actively participating in union affairs. We don’t think the group represents all the workers’ sentiments. We are open to all talks and possibilities,” he added.

The Homeplus union said its members will fight until all workers are guaranteed a good working environment. “We are asking for the company to adopt the same payroll for the same duties, adoption of summer vacations, and a uniform for everyone,” it added.

Homeplus’ biggest market rival and leader E-Mart last April upgraded its contract by transferring 9,100 temporary workers to permanent status and guaranteeing eight-hour working schedules, which include transition time and coffee breaks. Lotte Mart also grants its irregular workers with the same working hours as regular workers.

By Bae Ji-sook (baejisook@heraldcorp.com)