Prime Minister Junichiro Koizumi voiced reluctance Wednesday about increasing the number of foreign workers in Japan, citing concerns it would cause more social conflicts and crime.

"Conflicts inevitably occur when foreign workers increase to a certain level," Koizumi told a House of Representatives Budget Committee session. "The idea of supplementing labor shortages by easily accepting (foreign labor) should be carefully considered."

The prime minister stressed that a significant number of undocumented workers are already in Japan and that such people tend to find it hard to get a job due to their illegal status. They may end up getting involved in crime to earn money and escape justice, he said.

"If we open up to foreign labor at once, it would be good for (securing) the labor supply but could do more harm than good if crime increases," he said.

Koizumi's comments were in response to a question by ex-labor minister Chikara Sakaguchi of New Komeito.