China began blocking certain Japanese imports this week in a move widely regarded as retaliation for emergency tariffs Japan imposed on three Chinese exports on April 23.

Import inspection offices in Guangdong Province, China's predominant trading center, are holding up a wide range of Japanese imports packed in wooden crates by refusing to issue paperwork certifying they have been properly fumigated. One official from China's State Administration for Entry-Exit Inspection and Quarantine insisted the measure was impartial.

"It is the same for every country, aimed at keeping out harmful insects in the wood. This measure has nothing to do with Japanese safeguards against China," he told Kyodo News.

But 180 Japanese-affiliated firms in Guangdong have petitioned Tokyo's Consulate in Guangzhou to complain that only Japanese imports have been targeted, beginning the day after Japan imposed safeguard curbs on three agricultural products, the bulk of which come from China.