By Risa Maeda TOKYO, Sept 26 (Reuters) - Japan will resist pressure to relax import rules on beef from the United States, one of the nation's top suppliers of the meat before a ban several years ago, the new farm minister said on Wednesday. Agriculture Minister Masatoshi Wakabayashi, who was retained in his post after the new prime minister, Yasuo Fukuda, picked his cabinet on Tuesday, was referring to the United States urging trading partners to abolish age limits for cattle for beef exports. Japan currently limits American beef supplies to cattle aged 20 months or younger, a restriction that replaces a total ban on American beef after the United States discovered its first case of mad cow disease in December 2003. "If the U.S. uses political pressure to solve (the rift between Japan and the United States), that would be in vain," Wakabayashi, 73, said at a news conference. "I repeat that that would be a wasteful approach. Our basic stance is the same and unchanged," he said. Wakabayashi, who became farm minister in early September, reiterated his earlier comments, saying Japan must make its decision based on scientific facts. Japanese government officials have been studying data provided by their U.S. counterparts to decide whether to keep the age limit. Wakabayashi said the United States has been asking Japan to accept U.S. meat from cattle of all ages given a recent decision by the World Organization for Animal Health (OIE), which gave the United States a "controlled risk" status for beef safety. U.S. officials have said that the ranking shows their beef is safe and that trading partners should open their markets. Earlier this month, Costa Rica said it would resume imports of U.S. beef from animals born after a feed ban was put in place in 1997. It is believed feed contaminated by cattle parts is one way to spread the mad cow disease, also known as bovine spongiform encephalopathy. Wakabayashi three weeks ago replaced scandal-tainted Takehiko Endo, who resigned just a week after Shinzo Abe revamped his cabinet to regain public confidence. In Abe's first cabinet, Wakabayashi was also temporarily farm minister in August while at the same time serving as environmental minister. This unusual arrangement came after Endo's immediate two predecessors were tainted by political corruption scandals. One of them committed suicide, while another was virtually sacked. "I'm glad that I'm a starting member this time.... I'll be fully involved in the job," said Wakabayashi, who comes from Nagano prefecture in central Japan. "I'll brace myself for the important stage of farm policy," he added. Japan's farm policy is at a turning point as a subsidies reform started this year faced criticism in rural areas, contributing to the electoral defeat of Abe's coalition in July.