MINAMATA, Kumamoto Pref. -- Japan marked on Monday the 50th anniversary of the recognition of Minamata disease, a malady caused by pollution that officials were slow to confront and whose sufferers include thousands still seeking recognition and compensation.

About 600 people, including victims from around the country, attended a memorial service in this town along Minamata Bay that became infamous for the mercury poisoning from a Chisso Corp. plant. Officials originally expected about 1,000 people, but occasional rain and strong winds may have kept some people away.

Environment Minister Yuriko Koike and Chisso Chairman Shunkichi Goto, whose plant, which dates to the early 1930s, was blamed for causing the tragedy by dumping organic mercury into the bay for decades, were among the attendees. Although May 1 is the day the disease was officially recognized, the outbreak was believed to have occurred years earlier.