Government officers enforcing the minimum wage have restored £4 million in unpaid wages, the DTI announced on the second anniversary of its introduction.
Officials retrieved around £3 million last year after receiving thousands of telephone tip-offs on a special helpline.
The Government has received more than 6,000 complaints since the introduction of the minimum wage in April 1999.
Regional inspectors spot-checked 8,700 employers suspected of paying workers below the minimum wage and issued 342 enforcement notices and 54 penalty notices.
The minimum wage is set to rise again in October to £4.10 from the current rate of £3.70.