An anti-nuclear group Physicians for Social Responsibility, warned that radiation could be a long-term health hazard. Reuters

An explosion at the nuclear reactor in Fukushima, Japan, led to leakage of radiation from the facility.

Amidst fears of a disastrous meltdown at the plant, nearby areas, up to a distance of 10 kilometers from the facility were evacuated. The explosion which destroyed the walls of the No.1 reactor building injured a number of workers.

We are looking into the cause and the situation and we'll make that public when we have further information, Chief Cabinet Secretary Yukio Edano informed Reuters.

TV footage showed smoke rising from the 40-year-old Daiichi 1 reactor plant in Fukushima, which is 150 miles north of Tokyo.

As an aftershock of the massive 8.9 magnitude earthquake that struck Japan, officials reported that the air cooling system in the building probably failed leading to pressure rise. This, in turn, may have led to the gradual release of radioactive air and subsequently the explosion.