"But loopholes in the policy make them no-visa and illegal immigrants."
The number of migrant workers is increasing because of South Korea's low birthrate and shrinking labour force.
The labour ministry said 1.1 million foreigners live in the country, of whom 700,000 from 15 countries are classified as migrant workers.
Speakers told of problems such as discrimination and delayed payment of wages, in addition to difficulties switching jobs.
Prema Lal, from Sri Lanka, said attitudes had improved but bosses or Korean colleagues were sometimes disrespectful, especially to women.
Aung Tin Htun said many migrant agricultural workers are fired during the winter and cannot find jobs till the following summer. But regulations state they must find a new job within two months if they want to stay."This clearly reflects the reality of the Korean government treating migrant workers as day labourers," he said. "We urge Korea to assure the rights of Asian migrant workers."
The forum recommended better education for workers and bosses and called for migrant workers to be allowed to stay up to five years without having to file for an extension of stay.
The forum also urged more flexibility on visa expirations and on transfers to a new workplace.