Plutonium found in soil at the Fukushima nuclear complex heightened alarm on Tuesday over Japan’s battle to contain the world’s worst atomic crisis in 25 years, as pressure mounted on the prime minister to widen an evacuation zone around the plant.

Some opposition lawmakers blasted Naoto Kan in parliament for his handling of the disaster and for not widening the exclusion zone. Kan said he was seeking advice on such a step, which would force 130,000 people to move in addition to 70,000 already displaced.

The drama at the six-reactor facility has compounded Japan’s agony after an earthquake and tsunami on March 11 left more than 28,000 people dead or missing in the devastated northeast.