The U.S. Army conducted experiments with biological weapons on Taiwan and the Japanese island of Okinawa at the beginning of the 1960s, according to U.S. documents revealed Sunday by the Kyodo news agency.

In the tests, which were undertaken at least 12 times in 1961-1962, the fungus Magnaporthe grisea was sprayed on rice fields to see how it affected production, the documents say.

The U.S. government earlier had revealed details of other experiments with chemical and biological weapons in Puerto Rico, as well as in the states of Hawaii and Utah.

Japan's Okinawa archipelago was under U.S. control until 1972 and currently it houses more than half of the roughly 48,000 troops the United States keeps on Japanese territory, and 20 percent of the main island's territory is U.S. military terrain.

According to Kyodo, it is believed that the United States was developing agents that would damage rice cultivation with an eye toward potentially attacking China or Southeast Asia.

The U.S. government put an end to its chemical and biological weapons program in 1969.

The documents obtained by Kyodo mention locations such as the cities of Nago and Siri, both in Okinawa prefecture, but it is not known if the experiments were carried out on the U.S. military bases in the area or on civilian territory.

The army used different amounts of the chemical agents on different rice fields so as to measure their effect on crop cultivation, the document says.

Another document specifies that tests using wheat stem rust and the abovementioned fungus on rice were performed in different areas of the U.S. Midwest and South and in Okinawa with partial success in terms of the "useful information" gleaned from them. EFE