A class action lawsuit against nuclear suppliers General Electric, Toshiba and Hitachi has ballooned to more than 4,000 claimants who are seeking damages over the Fukushima atomic disaster, the lead lawyer said Wednesday.

The claimants, hailing from Japan and 32 other countries including the United States, Germany and South Korea, want the US and Japanese nuclear power plant suppliers to pay compensation, lawyer Akihiro Shima told media in Tokyo.

His comments came one day after the third anniversary of the world's worst nuclear disaster in a generation.

The filing -- which asks for a largely symbolic 100 yen ($1) per claimant -- was described by Shima as the first lawsuit to be brought against nuclear power-plant suppliers over the 2011 accident.

It alleges that the firms did not make necessary safety updates to the stricken site, which was swamped by an earthquake-sparked tsunami. Embattled plant operator Tokyo Electric Power is facing massive lawsuits and compensation costs.

"General Electric, Toshiba and Hitachi failed to implement safety improvements to the four-decades old boiling water reactors at the Fukushima Dai-ichi power plant," a statement issued Wednesday alleged.

"The lawsuit is intended to bring attention to the system that protects the nuclear industry around the world," it added.

The lawsuit was first filed in Tokyo District Court in January with just over 1,000 claimants, but many more have joined as word has spread.

Under Japanese law, nuclear plant suppliers are usually exempt from damage claims in the event of an accident.

"It is not our policy to comment on pending legal actions," GE's Japanese unit said in a statement when contacted by AFP.

But it added that the plant, which GE helped design, "has performed reliably for more than 40 years".

It also cited a Japanese government report which "concluded that the accident was caused by the tsunami, and the resulting loss of seawater pumps and all electrical power, not reactor design".

Toshiba and Hitachi both declined to comment.

On March 11, 2011, a 9.0-magnitude undersea earthquake sent a massive tsunami barrelling into Japan's Pacific coastline, sweeping away more than 18,000 victims and destroying coastal communities.

The huge waves swamped cooling systems at the Fukushima plant, sparking reactor meltdowns and explosions that spewed radioactive materials across the vast farm region.

Although no one died as a direct result of the atomic accident, at least 1,656 Fukushima residents died due to complications related to stress and other conditions.

Tens of thousands were forced to evacuate the area and may never be able to return home.