Unionized parcel delivery workers hold a rally in front of CJ Logistics' headquarters in Seoul to urge the company to scrap its plan to provide parcel delivery services seven days a week in this Oct. 21 photo. Yonhap

Logistics firms are facing intensifying disputes with delivery workers over the provision of parcel delivery services on Sundays and national holidays.

Despite concerns from delivery workers about overwork, an increasing number of companies are planning to offer seven-day-a-week delivery services to attract consumers seeking faster delivery.

On Wednesday, unionized delivery workers at CJ Logistics urged the company to scrap its plan to start delivering parcels every day starting in 2025.

In an apparent attempt to curb the rapid growth of Coupang, which has delivered goods seven days a week since 2015, CJ Logistics announced the plan in August, promising that its delivery workers would work five days a week in shifts.

However, its delivery workers pointed out that the new shift system will force each one of a four-member team to cover for his/her three other off-duty colleagues on Sundays and Mondays.

"The management has refused to answer the union's question about its plan to hire additional workers," said the leader of CJ Logistics' unionized delivery workers.

CJ Logistics is set to hold the fifth round of negotiations with the union on Nov. 19.

If they fail to reach an agreement, the delivery workers will hold a rally in front of the company's headquarters in Seoul, Nov. 24, about a month after they held a rally at the same place for the same reason on Oct. 21.

On Tuesday, unionized delivery workers at Lotte Global Logistics, Hanjin Logistics and Logen asked the companies to participate in negotiations with them and make it clear whether the companies will also provide parcel delivery services seven days a week.

A day later, Hanjin Logistics CEO Noh Sam-sug told reporters that the company is also considering delivering goods on Sundays.

"Our main focus is our customers, so we will also provide parcel delivery services seven days a week if they want," he said during a press conference on smart technologies for the company's warehouses. "However, sellers will need to work on weekends. Delivery workers, who have worked six days a week may also face decreasing incomes, if they work five days a week."