South Korean steelmaker Posco has sent its employees a tough no smoking message and may require them to take blood tests to check if they have kicked the habit.

Company officials said Tuesday that CEO Chung Joon-yang wants Posco, which employs 16,000 people, to be smoke-free by the end of year. Chung says the company may conduct blood tests to determine whether they have really given up tobacco.

The company's union and the Health Ministry have welcomed the campaign.

But Noh Hee-bum, a spokesman at the Constitutional Court, says the move could violate South Korea's Constitution, which guarantees the people's right to seek happiness.