TOKYO (AFP) - A limited amount of plutonium has been detected in soil outside Japan's troubled Fukushima nuclear power plant which was crippled by the March 11 quake-tsunami disaster, the government said Friday. It was the first time plutonium had been found in government tests outside the plant, presumably due to the nuclear accident, the worst since 1986 Chernobyl, the education and science ministry said in a statement. Plutonium was detected in soil at six places in a survey which was conducted in June in an area within 80 kilometres (50 miles) from the Fukushima Daiichi plant, the ministry said. Nuclear reactors at the plant suffered meltdowns after cooling systems knocked out .