Reactor number one at the tsunami-damaged Fukushima nuclear plant in Japan is to be covered with a huge tent to help contain radiation.

Tepco Electric Power say a contractor working at the plant died on Saturday, bringing the death toll to three, although the cause of the latest fatality is unknown.

The company plans to cover three of the four damaged reactors by the end of the year, starting with number one.

A steel frame will be erected first, which workers will then cover with polyester, with a ventilator and filter to capture radioactive material.

The environmental campaigners Greenpeace claim to have found alarmingly high levels of radiation in seaweed off the coast of Fukushima.

The group has also been checking fish for fall-out levels.

A spokesman for the Japanese Prime Minister said they will not ignore the research, but that they will have to establish that it was done in what he called an appropriate way.