A recent report shows that workers at small- and medium-sized firms are not only making less money than their counterparts at large conglomerates, but that the wage gap is growing.

The difference in salaries has widened over the past decade, the labor ministry said on Tuesday.

Workers at small companies were paid an average of W2.6 million a month between January and November last year (US$1=W1,123). This is nearly 40 percent less than the average monthly wage of employees at larger companies. Small companies are defined as firms that have fewer than 300 employees.