TAIWAN businessmen should suspend plans for investment in China until a boat fire that claimed the lives of 24 nationals is explained by mainland authorities, Economic Minister Chiang Ping-kun has said. His ministry is also considering screening applications of China-bound projects pending the result of an investigation into the Qiandao Lake disaster in Zhejiang province on March 31, Mr Chiang said. He warned Taiwan investors of high risks involved in operating on the mainland and asked them to ''suspend new investment or expansion plans in China'' until the incident is cleared up. Relatives of the victims, who had been rudely treated in Qingdao Lake, are scheduled to return to Taiwan via Hong Kong today. They plan to hold a press conference to tell of their plight. A vice-secretary general of Taiwan's Straits Exchange Foundation, who arrived in Hong Kong yesterday to help the families, said the mainland's handling of the case had hurt relations between the two sides.