Unionized delivery workers have begun voting on whether to launch a general strike after a social consultative body failed to reach an agreement on ways to improve working conditions.

A union official said Wednesday that voting has begun at some 200 polling sites set up nationwide at terminals and post offices. Some 55-hundred workers from five major logistics firms will take part in the vote that will be open for 48 hours until 12 a.m. Thursday.

If the outcome supports a general strike, collective action will begin January 27.

Delivery workers last week threatened a strike unless measures to prevent overwork are implemented before next month's Lunar New Year holiday when parcel deliveries spike in volume.

They have been struggling with an excessive workload amid a surge in online orders during the pandemic. Their demands include suspending overnight deliveries, allowing for delivery delays, raising delivery fees and increasing the number of workers exclusively tasked with sorting parcels.