A government survey on convenience store operations showed Tuesday that most store owners are overworked, with 85 percent of them saying they work six days or more a week.

The Economy, Trade and Industry Ministry has been surveying working conditions in the convenience store industry as problems associated with 24/7 operations and long working hours have surfaced amid the country's labor crunch.

The survey was conducted in August on 3,645 franchise store owners and 500 employees.

According to the survey, 66 percent of store owners said they have "less than a day" off from work per week, and 19 percent have one day off.

As for work hours, 29 percent of store owners and 56 percent of store owners' family members who help run the outlets said they work 12 hours or longer a day.

Many store owners surveyed complained of a heavy workload because their duties include not only attending to customers but restocking merchandise which is typically delivered during late hours.

Many questioned the need to keep running stores 24 hours a day due to the high personnel cost of keeping them open during slow hours, according to the survey.

In a multiple choice question for employees about workplace challenges, 64 percent of the respondents picked labor shortage, 33 percent late night operations and 29 percent food waste.

The ministry plans to directly hear from officials of eight major convenience store operators including Seven-Eleven Japan Co. and Lawson Inc. this month about their 24-hour operation policy, profit distribution between franchisees and their emergency preparedness.